SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY OF SOME NEW BAYLIS-HILLMAN DERIVED CINNAMYL SUBSTITUTED QUINAZOLINONE DERIVATIVES

SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY OF SOME NEW BAYLIS-HILLMAN DERIVED CINNAMYL SUBSTITUTED QUINAZOLINONE DERIVATIVES

Lavanya Devi Chebrolu ^{* 1}, Usha Kiranmayi Obulapu Marta Jhansi ², Ramesh Vadla ¹, Sridhar Balasubramanian ³, Jayathirtha Rao Vidya ¹ and Surya Narayana Murthy Upadhyayula ²

Crop Protection Chemicals Division ¹, Biology Division ², X-ray Crystallography ³, Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad - 500 607, Telangana, India.

ABSTRACT: A series of new Baylis–Hillman derived cinnamyl substituted quinazolinone derivatives have been synthesized by the condensation reaction between Baylis-Hillman bromides and quinazolinones in a simple and efficient manner in less reaction time with high yields. Methyl quinazolinone yields two isomers of Baylis-Hillman derived 3-N-cinnamyl substituted quinazoline-4-one derivatives and 4-O-cinnamyl substituted quinazoline derivatives, and the structures were confirmed by X-ray crystallography. All the newly synthesized compounds were characterized by their spectral data and evaluated their antibacterial and antifungal activity. The compounds (3a, 4a) without any substitution at the aryl group exhibited good antibacterial activity especially on S. epidermidis (gram positive), Replacement of hydrogen atom of the aryl group by CF₃ (3c, 4c) or by fluorine (3g) exhibited significant antibacterial activity on both gram-positive (S. epidermidis) and gram-negative (K. pneumonia) organisms compared to other compounds. All the compounds exhibited interesting antifungal activity on C. albicans microorganism exclusively and inactive on the remaining organisms. Compound 3a and 4f exhibited good antifungal activity compared to the other compounds.

Quinazolinone, Quinazoline, Baylis–Hillman Bromides, Antimicrobial activity

INTRODUCTION: Research in heterocyclic chemistry has gained thrust in recent times because more than half of the biologically active molecules belong to various classes of heterocycles ^1-8. 1, 3-Diaza-heterocycles like pyrimidine and quinazoline derivatives, quinazolinones in particular, have been identified as potential drug molecules against various types of diseases. Innumerable quinazolinone alkaloids isolated from plants, animals, and microorganisms shows different types of pharmacological activities ^9-15.

Rutaecarpine and Evodiamine Fig. 1, alkaloidal constituents of the Chinese herbal drugs Wu-Chu- Ru ^{16, 17} Shih-Hu ^{18, 19}  and Febrifugine ²⁰ alkaloids isolated from roots of the Dichroa Febrifuga plant contain the quinazolinone ring system in their structures.

FIG. 1: BIOLOGICALLY ACTIVE QUINAZOLINONE DERIVATIVES

The unique scaffold and pharmacological properties associated with these types of compounds attracted the attention of chemists towards the syntheses of various types of analogs, and this led to the identification of novel quinazolinone derivatives showing a wide variety of activities like antiallergic, ²¹ anticonvulsant, ^22-24 sedative-hypnotic, ²⁵ antihypertensive ²⁶ and also anticancer ^{27, 28}, etc.

Antibacterial and antifungal diseases are very common all over the world. Currently used antimicrobial agents are not effective due to the resistance developed by the microbes, and therefore, it is an ongoing effort to synthesize new antimicrobial agents. Quinazolin-4(3H)-ones with substitution at position 3, has been reported to be associated with anti-microbial properties.^29-36 Examples of these substitutions were substituted phenyl ring moieties ^{29, 30} bridged phenyl rings ^{31, 32} heterocyclic rings 33 and aliphatic systems ^{34, 35}.

The Baylis–Hillman reaction ^37-41 has attracted the attention of organic chemists as this reaction provides synthetically useful multifunctional molecules. Inspired with the biological profile of quinazolinones and their increasing importance in pharmaceutical and biological fields, and in connection with our research on the design and synthesis of biologically active and pharmacologically important new heterocycles and their derivatives ^42-48 it was thought worthwhile to synthesize the title compounds with a view to obtain certain new chemical entities and to have them evaluated for their antimicrobial activity. On the other hand, to the best of my knowledge previously, there is no report, on the synthesis of Baylis-Hillman derived 3-substituted cinnamyl quinazolinone derivatives. In this article, we illustrate the simple and efficient synthesis of Baylis-Hillman derived 3-N-cinnamyl substituted quinazoline-4-one derivatives and 4-O-cinnamyl substituted quinazoline derivatives and screened for their antimicrobial activity.

EXPERIMENTAL:

Materials: All chemicals were of research grade and were used as obtained from Aldrich. The reactions were carried out in a round-bottomed flask of 25 ml capacity at room temperature in an efficient fume hood. The progress of all the reactions was monitored by TLC. Melting points were determined on a MEL-TEMP II melting point apparatus and were uncorrected. IR spectra were recorded on a Perkin-Elmer FT-IR spectrophotometer. ¹H and ¹³C NMR spectra were recorded on a Varian Gemini 200 MHz, Bruker Avance 300 MHz, 75 MHz spectrometers; TMS was used as an internal standard in CDCl₃. Mass spectra were recorded on VG Micro mass 7070 H (EI), QSTAR XL High-resolution mass spectrometer (HRMS), Thermo fining an ESI ion trap Mass Spectrometer and a GC-MS system on an Agilent 6890 series. Commercially available organic compounds were used without further purification except for the solvent, which was distilled by known methods before use. X-ray data were collected at room temperature using a Bruker Smart Apex CCD diffracto meter with graphite mono chromated Mo Ka radiation (l=0.71073Å) by the ω-scan method ⁴⁹.

Preliminary lattice parameters and orientation matrices were obtained from four sets of frames. Integration and scaling of intensity data were accomplished using the program SAINT ⁴⁹. The structures were solved by direct methods using SHELXS97 ⁵⁰ and refinement was carried out by full-matrix least-squares technique using SHELXL-97 ⁵⁰. Anisotropic displacement parameters were calculated for all non-hydrogen atoms. All H atoms were positioned geometrically and treated as riding on their parent C atoms, with C-H = 0.93-0.98 Å, and with U_iso (H) = 1.5U_eq(C) for methyl H and 1.2U_eq(c) for other H atoms. The methyl groups were allowed to rotate but not to tip.

General Experimental Procedure: To a solution of quinazolin-4(3H)-one 2a (0.292 g, 2 mmol) in DMF (3 mL), oven dried and ground K₂CO₃ (0.331 g, 1.2 mmol) was added and stirred at room temperature for 10 minutes. Bayllis Hillman bromide (Z)- methyl 2- (bromomethyl)-3-phenylacrylate 1a (0.51 g, 2 mmol) in 2ml DMF was added slowly and stirred at room temperature. Progress of the reaction was monitored by TLC. After completion (1 h), the reaction mixture was diluted with water to remove excess K₂CO₃ and the obtained solid was filtered, washed with water and dried to obtain compound 3a in 95% yield. A similar procedure was adopted for the preparation of other quinazolinone derivatives. In case of compounds 3i-j the obtained solid was further purified by recrystallization with hexane: ethyl acetate (3:1) to get exclusively Z-isomer.

In case of compounds 4a-f and 5a-f the obtained solid mixture was further purified by column chromatography (60-120) mesh, with eluent, hexane: ethyl acetate and the pure compounds of 4a-f (8:2) and 5a-f (7:3) were separated.

(E)-methyl2-((4-oxoquinazolin-3(4H)-yl)methyl)-3-phenylacrylate (3a): ¹H NMR (DMSO-d₆, 300 MHz): d 3.75 (s, 3H, O-CH₃), 4.99 (s, 2H, N-CH₂), 7.34-7.37 (t, 1H, J = 7.78 Hz, H_Ar), 7.39-7.44 (q, 3H, J = 8.49 Hz, H_Ar), 7.52-7.54 (d, 2H, J = 7.78, H_Ar), 7.60-7.61 (d, 1H, J = 7.78 Hz, H_Ar), 7.68-7.71 (t, 1H, J = 7.78 Hz, H_Ar), 7.95 (s, 1H, C=CH), 8.09 (s, 1H, N=CH), 8.14-8.16 (d, 1H, J = 7.78 Hz, H_Ar).¹³C NMR (DMSO, 75 MHz): d 43.56 (O-CH₃), 51.57(N-CH₂), 121.37, 125.74, 126.20, 126.74, 128.14, 128.14, 128.67, 128.92, 133.37, 133.77, 143.13, 143.34, 147.07, 147.47, 159.91 (N-C=O), 166.0 (O-C=O). IR (KBr) in cm^-1: 1260 (C-O-C), 1471 (C=N), 1605 (C=C), 1696 (C=O), 2945 (=CH), 3057 (Ar-CH).MS-ESI: m/z 321 [M+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₁₉H₁₇N₂O₃: 321.1239; found 321.1252.

(E)-methyl 3- (4- methoxy phenyl) -2-((4-oxoquinazolin-3(4H)-yl) methyl) acrylate (3b): ¹H NMR (CDCl₃, 300 MHz,): d 3.78 (s, 3H, O-CH₃), 3.82 (s, 3H, Ar-O-CH₃), 5.04 (s, 2H, N-CH₂), 6.89-6.92 (m, 2H, H_Ar),  7.42-7.51 (m, 3H, H_Ar), 7.63-7.73 (m, 2H, H_Ar), 7.96 (s, 1H, C=CH), 8.07 (s, 1H, N=CH), 8.23-8.27 (d, 1H, J = 8.31 Hz, H_Ar).¹³C NMR (CDCl₃,75 MHz,): d 43.74 (O-CH₃), 52.29 (Ar-O-CH₃), 55.29 (N-CH₂), 121.95, 122.80, 126.35, 126.62, 127.02, 127.33, 131.52, 134.11, 145.34, 145.34, 146.28, 147.90, 160.79 (O-Ar-C), 161.22 (O=C-N), 167.31 (O=C-O).IR (KBr) in cm^-1: 1258 (C-O-C), 1470 (C=N), 1601 (C=C), 1699 (C=O), 2841 (=CH), 2942 (Ar-CH).MS-ESI: m/z 351 [M+H]⁺.HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₀H₁₉N₂O₄Br: 351.1344; found 351.1359.

(E)-methyl2-((4-oxoquinazolin-3(4H)-yl)methyl)-3 (2 (tri fluoro methyl) phenyl) acrylate (3c):¹H NMR (CDCl₃, 300 MHz,): d 3.81 (s, 3H, O-CH₃), 4.77 (s, 2H, CH₂), 7.40-7.49 (m, 2H, H_Ar), 7.57-7.64 (m, 2H, H_Ar), 7.66-7.76 (m, 3H, H_Ar), 8.01 (s, 1H, C=CH), 8.05 (s, 1H, N=CH), 8.17-8.19 (dd, 1H, J = 7.93 Hz, H_Ar).¹³C NMR (CDCl₃, 75 MHz): d 43.81 (CH₂), 52.56 (CH₃), 121.95, 125.07, 126.12, 126.19, 126.62, 127.08, 127.38, 128.86, 129.14, 129.14, 129.88, 131.90, 132.79, 134.14, 141.21, 146.88, 160.83 (O=C-N), 166.12 (O=C-O). IR (KBr) in cm^-1: 1258 (C-O-C), 1293, 1319, 1473 (C=N), 1606 (C=C), 1679 (N-C=O), 1710 (O-C=O), 2955 (=CH), 3073 (Ar-CH).MS-ESI: m/z 389 [M+H]⁺.HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₀H₁₆N₃O₃F₃: 389.1113; found 389.1117.

(E)-methyl 3- (4-nitro phenyl) -2- ((4-oxo quinazolin-3(4H)-yl)methyl) acrylate (3d): ¹H NMR (CDCl₃, 300 MHz,): d 3.78 (s, 3H, O-CH3), 4.95 (s, 2H, N-CH₂), 7.41-7.46 (t, 1H, J =8.31 Hz, H_Ar), 7.60-7.62 (d, 1H, J = 7.55 Hz, H_Ar), 7.69-7.73 (t, 1H, J = 6.80 Hz, H_Ar), 7.81-7.84 (d, 2H, J = 8.31 Hz, H_Ar), 7.93 (s, 1H, C=CH), 8.08-8.11 (d, 1H, J = 8.31 Hz, H_Ar), 8.22-8.25 (d, 2H, J = 6.80 Hz, H_Ar), 8.28 (s, 1H, N=CH). ¹³C NMR (CDCl₃, 75 MHz): d 44.28 (O-CH₃), 52.57 (N-CH₂), 121.72, 123.77, 126.41, 127.21, 127.36, 128.82, 129.90, 134.32, 140.85, 141.79, 147.28, 147.68, 147.74, 161.06 (N-C=O), 166.18 (O-C=O). IR (KBr) in cm^-1: 1260 (C-O-C), 1472 (C=N), 1517, 1609 (C=C), 1675 (N-C=O), 1707 (O-C=O), 2957 (=CH), 3061 (Ar-CH).MS-ESI: m/z 366 [M+H]⁺.HRMS (ESI): m/z, (M+H)⁺ calculated for C₁₉H₁₆N₃O₅: 366.1089; found 366.1081.

(E)-methyl 3- (naphthalen-1-yl) -2-((4-oxo quinazolin-3(4H)-yl) methyl) acrylate (3e): ¹H NMR (CDCl₃, 300 MHz,): d 3.85 (s, 3H, O-CH₃), 4.89 (s, 2H, N-CH₂), 7.36-7.39 (t, 1H, J = 7.29 Hz, H_Ar), 7.43-7.45 (dd, 2H, J = 8.33 Hz, H_Ar), 7.47-7.48 (d, 1H, J = 7.29 Hz, H_Ar), 7.51-7.53 (m, 2H, H_Ar), 7.96 (s, 1H), 7.62-7.65 (t, 1H, J = 8.33 Hz, H_Ar), 7.75 (s, 1H, C=CH), 7.78-7.83 (m, 3H, H_Ar), 8.11-8.13 (d, 1H, J = 8.33 Hz, H_Ar), 8.43 (s, 1H, N=CH).¹³C NMR (CDCl₃, 75 MHz,): d 44.27 (O-CH₃), 52.86 (N-CH₂), 122.42, 124.36, 125.20, 126.03, 126.43, 126.67, 126.79, 126.86, 127.28, 128.65, 129.55, 131.09, 131.57, 133.44, 133.87, 143.04, 143.90, 146.81, 148.16, 160.99 (N-C=O), 166.80 (O-C=O).IR (KBr) in cm^-1: 1274 (C-O-C), 1468 (C=N), 1606 (C=C), 1700 (C=O), 2954 (=CH), 3057 (Ar-CH).MS-ESI: m/z 371 [M+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₃H₁₉N₂O₃: 371.1395; found 371.1408.

(E)-ethyl 3- (4-bromo phenyl) -2- ((4-oxoquinazolin-3(4H)-yl) methyl) acrylate (3f): ¹H NMR (DMSO-d₆, 300 MHz,): d 1.26-1.29 (t, 3H, J = 7.13 Hz, CH₃), 4.17-4.21 (q, 2H, J = 7.13 Hz, O-CH₂), 5.01 (s, 2H, N-CH₂), 7.47-7.50 (t, 1H, J = 7.92 Hz, H_Ar),  7.57-7.61 (q, 4H, J = 8.71 Hz, H_Ar), 7.63-7.65 (d, 1H, J = 7.92 Hz, H_Ar), 7.74-7.77 (t, 1H, J = 7.92 Hz, H_Ar), 7.85 (s, 1H,C =CH), 8.13-8.14 (d, 1H, J = 7.92, H_Ar), 8.23 (s, 1H, N=CH).¹³C NMR (DMSO-d6, 75 MHz): d 12.67 (CH₃), 42.69(O-CH₂), 59.72 (N-CH₂), 120.35, 121.73, 124.82, 125.44, 125.82, 129.61, 129.76, 130.29, 131.96, 132.63, 140.93, 146.40, 146.46, 159.19 (N-C=O), 164.48 (O-C=O).IR (KBr) in cm^-1: 1256(C-O-C), 1469  (C=N), 1606 (C=C), 1686 (N-C=O), 1715 (O-C=O), 2977 (=CH).MS-ESI: m/z 413 [M+H]⁺, 415 [M+2+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₀H₁₈N₂O₃Br: 413.0500; found 413.0521.

(E)-methyl 3- (4- fluoro phenyl) -2- ((4-oxoquinazolin-3(4H)-yl) methyl) acrylate (3g): ¹H NMR (CDCl₃, 300 MHz,): d 3.78 (s, 3H, O-CH₃), 4.97 (s, 2H, N-CH₂), 7.09-7.15 (t, 2H, J = 8.31 Hz, H_Ar), 7.42-7.47 (td, 1H, J = 6.80 Hz, H_Ar),  7.57-7.61 (q, 2H, J = 5.29 Hz, H_Ar), 7.63-7.74 (m, 2H, J = 8.31 Hz, H_Ar), 7.93 (s, 1H, C=CH), 8.10 (s, 1H, N=CH), 8.20-8.23 (d, 1H, J = 7.55 Hz, H_Ar).¹³C NMR (CDCl₃, 75 MHz): d 43.94 (O-CH₃), 52.39 (N-CH₂), 115.85, 116.14, 121.91, 125.58, 126.57, 127.12, 127.37, 130.22, 131.46, 134.21, 143.93, 146.83, 147.86, 161.18, 161.48, 164.81 (N-C=O), 166.85 (O-C=O).IR (KBr) in cm^-1: 1264 (C-O-C), 1469 (C=N), 1605 (C=C), 1691(C=O), 2951 (=CH), 3050(Ar-CH).MS-ESI: m/z 339 [M+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₁₉H₁₆N₂O₃F: 339.1144; found 339.1137.

(E)-methyl 2- ((4- oxo quinazolin-3 (4H)-yl)methyl)-3-(thiophen-2-yl) acrylate (3h): ¹H NMR (CDCl₃, 300 MHz): d 3.79 (s, 3H, O-CH₃), 5.15 (s, 2H, N-CH₂), 7.11-7.14 (dd, 1H, J = 5.29 Hz, H_Ar), 7.42-7.49 (m, 2H, H_Ar), 7.54-7.56 (d, 1H, J = 5.29 Hz, H_Ar), 7.64-7.73 (m, 2H, H_Ar), 8.09 (s, 1H, C=CH), 8.11 (s, 1H, N=CH), 8.25-8.28 (d, 1H, J = 8.31 Hz, H_Ar). ¹³C NMR (CDCl₃, 75 MHz,): d 44.10 (O-CH₃), 52.36 (N-CH₂), 120.85, 122.15, 126.83, 126.93, 127.55, 127.75, 131.39, 133.96, 134.57, 136.78, 137.39, 146.14, 148.14, 161.09 (N-C=O), 166.98 (O-C=O). IR (KBr) in cm^-1: 1204 (C-O-C), 1471(C=N), 1607 (C=C), 1672 (N-C=O), 1716 (O-C=O), 2920 (=CH), 3106 (Ar-CH).MS-ESI: m/z 327[M+H]⁺.HRMS (ESI): m/z, (M+H)⁺ calculated for C₁₇H₁₅N₂O₃S: 327.0803; found 327.0814.

(Z)-3- (4-nitro phenyl) -2- ((4- oxo quinazolin 3 (4H)-yl) methyl) acrylo nitrile (3i): ¹HNMR (CDCl₃, 300 MHz): d 5.04 (s, 2H, N-CH₂), 7.50-7.54 (t, 1H, J = 7.35 Hz, H_Ar), 7.65 (s, 1H, C=CH), 7.69-7.71 (d, 1H, J = 7.35 Hz, H_Ar), 7.77-7.81 (t, 1H, J = 8.39 Hz, H_Ar), 7.99-8.0 (d, 2H, J = 9.44 Hz, H_Ar), 8.22-8.24 (d, 2H, J = 8.39 Hz, H_Ar), 8.27-8.29 (d, 2H, J = 8.39 Hz, H_Ar), 8.42(s, 1H, N=CH).¹³C NMR (CDCl₃, 75 MHz,): d 48.29 (N-CH₂), 109.97, 116.10, 121.34, 123.52, 125.99, 126.78, 127.07, 129.63, 134.03, 138.62, 144.06, 146.76, 147.64, 147.76, 159.80 (N-C=O). IR (KBr) in cm^-1: 1471 (C=N), 1518, 1605 (C=C), 1666 (N-C=O), 2216 (CºN), 2995 (=CH), 3036 (Ar-CH). MS-ESI: m/z 338[M+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₂H₁₆N₃O: 338.1293; found 338.1307.

(Z) - 3- (4-bromo phenyl)- 2- ((4-oxo quinazolin 3(4H)-yl) methyl) acrylo nitrile (3j): ¹H NMR (CDCl₃, 300 MHz): d 4.98 (s, 2H, N-CH₂), 7.44-7.60 (m, 4H, H_Ar), 7.67-7.70 (d, 3H, J = 8.31 Hz, H_Ar), 7.75-7.81 (m, 3H, H_Ar), 8.2-8.23 (d, 1H, J = 7.93 Hz, H_Ar), 8.39 (s, 1H, N=CH). ¹³C NMR (75 MHz, CDCl₃): d 49.88 (N-CH₂), 105.19, 117.02, 121.88, 125.82, 126.75, 127.75, 127.84, 130.58, 131.19, 132.27, 134.76, 145.38, 146.94, 147.99, 160.85 (N-C=O). IR (KBr) in cm^-1: 1350, 1473 (C=N), 1606 (C=C), 1663 (N-C=O), 2211 (CºN), 2925 (=CH).MS-ESI: m/z 366 [M+H]⁺, 368 [M+2+H]⁺.HRMS (ESI): m/z, (M+H)⁺ calculated for C₁₈H₁₃N₃OBr: 366.0241; found 366.0229.

(E)-methyl 2-((2-methyl-4-oxoquinazolin-3(4H)-yl) methyl)-3-phenyl acrylate (4a): ¹H NMR (CDCl₃, 300 MHz): d 2.51 (s, 3H, C-CH₃), 3.70 (s, 3H, O-CH₃), 5.18 (s, 2H, N-CH₂), 7.18-7.37 (m, 5H, H_Ar), 7.47-7.49 (d, 1H,  J = 7.55 Hz, H_Ar), 7.60-7.66 (dt, 1H, J = 1.51 Hz, J = 8.31 Hz, H_Ar), 7.87(s, 1H, C=CH), 8.10-8.14 (dd, 1H, J = 1.51 Hz, J = 8.31 Hz, H_Ar). ¹³C NMR (75 MHz, CDCl₃): d 22.92 (CH₃), 41.37 (O-CH₃), 51.73 (N-CH₂), 119.92, 125.73, 126.03, 126.43, 127.31, 128.09, 128.24, 128.33, 133.62, 133.88, 142.11, 146.62, 154.16, 161.69 (N-C=O), 166.06 (O-C=O). IR (KBr) in cm^-1: 1249 (C-O-C), 1387, 1432, 1469 (C=N), 1591(C=C), 1676 (N-C=O), 1710 (O-C=O), 2947 (=CH). MS-ESI: m/z 335[M+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₀H₁₉N₂O₃: 335.1395; found 335.1399.

(E)-methyl 2- ((2-methyl quinazolin -4-yloxy) methyl)-3-phenyl acrylate (5a): ¹H NMR (CDCl₃, 300 MHz): d 2.67 (s, 3H, C-CH₃), 3.85 (s, 3H, O-CH₃), 5.39 (s, 2H, O-CH₂), 7.33-7.37 (m, 3H, H_Ar), 7.41-7.48 (m, 3H, H_Ar), 7.73-7.78 (dt, 1H, J = 1.51 Hz, J = 6.80 Hz, H_Ar), 7.81-7.83 (d, 1H, J = 7.55 Hz, H_Ar), 8.05 (s, 1H, C=CH), 8.08-8.10 (d, 1H, J = 7.55 Hz, H_Ar). ¹³C NMR (CDCl₃, 75 MHz): d 26.40 (CH₃), 52.3 (O-CH₃), 61.74 (O-CH₂), 114.66, 120.49, 123.54, 126.05, 127.11, 128.81, 129.65, 132.63, 133.40, 134.47, 145.91, 154.03, 161.46 (O-C=O), 165.53 (N-C=N), 166.50 (O-C=N). IR (KBr) in cm^-1: 1229 (C-O-C), 1376, 1425, 1494 (C=N), 1575, 1623 (C=C), 1711(O-C=O), 2953 (=CH). MS-ESI: m/z 335[M+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₀H₁₉N₂O₃: 335.1395; found 335.1397.

(E)-methyl 3-(4-methoxy phenyl)-2-((2-methy l-4-oxoquinazolin-3(4H) yl) methyl) acrylate (4b): ¹H NMR (CDCl3, 300 MHz): d 2.51 (s, 3H, C-CH₃), 3.65 (s, 3H, O-CH₃), 3.75 (s, 3H, ArO-CH₃), 5.21 (s, 2H, N-CH₂), 6.81-6.83 (d, 2H, J = 8.58 Hz, H_Ar), 7.33-7.36 (m, 3H, H_Ar), 7.48-7.49 (d, 1H, J = 7.62 Hz, H_Ar), 7.61-7.64 (dt, 1H, J = 1.91 Hz, J = 8.58 Hz, H_Ar), 7.81(s, 1H, C=CH), 8.12-8.14 (d, 1H, J = 7.62 Hz, H_Ar). ¹³C NMR (CDCl₃, 75 MHz): d 23.36 (CH₃), 41.63 (O-CH₃), 52.02 (ArO-CH₃), 55.22 (O-CH₂), 114.01, 125.71, 126.14, 126.41, 126.61, 126.84, 130.80, 134.03, 141.84, 142.58, 147.06, 154.74, 160.09 (O-CAr), 162.22 (N-C=O), 166.70 (O-C=O).IR (KBr) in cm^-1: 1260 (C-O-C), 1460 (C=N), 1511, 1600 (C=C), 1680 (N-C=O), 1715 (O-C=O), 2837, 2859 (=CH). MS-ESI: m/z 365[M+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₁H₂₁N₂O₄: 365.1501; found 365.1514.

(E)-methyl 3- (4-methoxyphenyl) -2- ((2-methyl quinazolin-4-yloxy) methyl) acrylate (5b): ¹H NMR (CDCl₃, 300 MHz): d 2.80 (s, 3H, CH₃), 3.81 (s, 3H, O-CH₃), 3.85 (s, 3H, ArO-CH₃), 5.48 (s, 2H, O-CH₂), 6.87-6.90 (d, 2H, J = 8.50 Hz, H_Ar), 7.43-7.46 (d, 2H, J = 8.69 Hz, H_Ar), 7.51-7.56 (t, 1H, J = 7.36 Hz, H_Ar), 7.83-7.88 (t, 1H, J = 7.18 Hz, H_Ar), 8.06 (s, 2H), 8.13-8.16 (d, 1H, J = 7.93 Hz, H_Ar). ¹³C NMR (CDCl₃, 75 MHz): d 26.37(CH₃), 52.25 (O-CH₃), 55.33 (ArO-CH₃), 61.98 (O-CH₂), 101.59, 114.27, 119.92, 123.52, 124.42, 126.08, 126.84, 129.27, 131.68, 133.49, 136.73, 145.88, 152.43, 160.92, 164.14, 166.14, 167.97. IR (KBr) in cm^-1: 1260 (C-O-C), 1306, 1372, 1436, 1505 (C=N), 1597 (C=C), 1712 (O-C=O), 2845, 2924 (=CH). MS-ESI: m/z 365 [M+H]⁺ HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₁H₂₁N₂O₄: 365.1501; found 365.1510.

(E)-methyl 2- ((2-methyl -4- oxo quinazolin-3(4H)-yl)methyl)-3-(2-(tri fluoro methyl) phenyl) acrylate (4c): ¹H NMR (CDCl₃, 300 MHz): d 2.50 (s, 3H, CH₃), 3.77 (s, 3H, O-CH₃), 5.02 (s, 2H, N-CH₂), 7.24-7.37 (m, 2H, H_Ar), 7.40-7.51 (m, 2H, H_Ar), 7.55-7.67 (m, 3H, H_Ar), 7.94 (s, 1H, C=CH), 8.05-8.08 (dd, 1H, J = 1.51, J = 8.31 Hz, H_Ar). ¹³C NMR (CDCl₃, 75 MHz): d 23.23(CH₃), 41.97 (O-CH₃), 52.49 (N-CH₂), 120.15, 125.78, 125.84, 125.92, 125.98, 126.19, 126.48, 126.75, 127.91, 128.49, 130.08, 131.06, 131.66, 132.56, 134.13, 138.68, 147.00, 154.48 (N-C=O), 166.05 (O-C=O). IR (KBr) in cm^-1: 1237 (C-O-C), 1316, 1375, 1416, 1492 (C=N), 1575 (C=C), 1671 (N-C=O), 1714 (O-C=O), 2954 (=CH), 3070 (ArCH). MS-ESI: m/z 403 [M+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₁H₁₈N₂O₃F₃: 403.1275; found 403.1275.

(E)-methyl 2-((2-methyl quinazolin - 4 yloxy) methyl)-3-(2-(tri fluoro methyl) phenyl) acrylate (5c): ¹H NMR (CDCl₃, 300 MHz): d 2.63 (s, 3H, CH₃), 3.89 (s, 3H, O-CH₃), 5.22 (s, 2H, N-CH₂), 7.40-7.48 (m, 4H, H_Ar), 7.68-7.83 (m, 3H, H_Ar), 8.01-8.03 (d, 1H, J = 7.55 Hz, H_Ar), 8.22-8.23 (d, 1H, J = 1.51 Hz, H_Ar). ¹³C NMR (CDCl₃, 75 MHz): d 26.31 (CH₃), 52.45 (O-CH₃), 61.42 (O-CH₂), 114.49, 121.99, 123.35, 125.62, 126.01, 126.12, 126.19, 127.15, 128.45, 128.92, 129.24, 130.19, 130.35, 131.83, 133.37, 141.85, 151.57, 163.49 (O-C=O), 165.71 (N=C-N), 166.27 (O-C=N). IR (KBr) in cm^-1: 1237 (C-O-C), 1316, 1375, 1416, 1492 (C=N), 1575, 1621(C=C), 1714 (O-C=O), 2954 (=CH), 3070 (Ar-CH). MS-ESI: m/z 403[M+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₁H₁₈N₂O₃F₃: 403.1269; found 403.1273.

(E)-methyl 2-((2-methyl-4-oxo quinazolin-3 (4H)-yl) methyl) - 3-(4-nitrophenyl) acrylate (4d): ¹H NMR (CDCl₃, 300 MHz): d 2.62 (s, 3H, CH₃), 3.80 (s, 3H, O-CH₃), 5.11 (s, 2H, N-CH₂), 7.30-7.35 (t, 1H, J = 7.55 Hz, H_Ar), 7.42-7.45 (d, 3H, J = 9.07 Hz, H_Ar), 7.59-7.64 (t, 1H, J = 8.31 Hz, H_Ar), 7.84 (s, 1H, C=CH), 7.96-8.0 (m, 3H, H_Ar). ¹³C NMR (CDCl₃, 75 MHz): d 23.44 (CH₃), 42.28 (O-CH₃), 52.58 (N-CH₂), 119.85, 123.34, 126.45, 126.49, 126.56, 128.75, 130.18, 134.40, 139.56, 140.83, 147.13, 146.86, 154.05, 161.96 (N-C=O), 165.95 (O-C=O). IR (KBr) in cm^-1: 1257 (C-O-C), 1340, 1509 (C=N), 1595 (C=C), 1677 (N-C=O), 1712 (O-C=O), 2953 (=CH). MS-ESI: m/z 380 [M+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₀H₁₇N₃O₅: 380.1246; found 380.1264.

(E)-methyl 2-((2-methyl quinazolin- 4 - yloxy) methyl)-3-(4-nitrophenyl) acrylate (5d): ¹H NMR (CDCl₃, 300 MHz): d 2.67 (s, 3H, CH₃), 3.89 (s, 3H, O-CH₃), 5.35 (s, 2H, O-CH₂), 7.42-7.49 (m, 1H, H_Ar), 7.52-7.54 (d, 2H, J = 8.31 Hz, H_Ar), 7.75-7.85 (m, 2H, H_Ar), 8.01-8.03 (d, 2H, J = 8.31 Hz, H_Ar), 8.19-8.24 (m, 2H, H_Ar). ¹³C NMR (75 MHz, CDCl₃): d 26.32 (CH₃), 52.66 (O-CH₃), 61.12 (O-CH₂), 114.36, 123.14, 123.94, 126.24, 127.21, 129.36, 130.18, 130.66, 133.66, 136.08, 142.53, 151.61, 163.52 (O-C=O), 165.61 (N-C=N), 166.66 (O-C=N). IR (KBr) in cm^-1: 1225 (C-O-C), 1342, 1424 (C=N), 1520, 1578, 1625 (C=C), 1719 (O-C=O), 2954. MS-ESI: m/z 380 [M+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₀H₁₇N₃O₅: 380.1246; found 380.1247.

(E)-methyl 2-((2-methyl-4-oxoquinazolin-3 (4H)-yl)methyl)-3-(naphthalen-1-yl) acrylate (4e): ¹H NMR (CDCl₃, 300 MHz,): d 2.26 (s, 3H, CH₃), 3.80 (s, 3H, O-CH₃), 5.06 (s, 2H, N-CH₂), 7.22-7.45 (m, 6H, H_Ar), 7.50-7.78 (m, 4H, H_Ar), 7.94-8.0 (d, 1H, J = 7.93 Hz, H_Ar), 8.25 (s, 1H, H_Ar). ¹³C NMR (CDCl₃, 75 MHz,): d 22.94 (CH₃), 41.92 (O-CH₃), 52.29 (N-CH₂), 119.98, 124.25, 124.85, 125.73, 125.93, 126.05, 126.19, 126.49, 126.63, 128.33, 128.87, 129.74, 131.21, 133.02, 133.78, 135.59, 140.92, 146.57, 154.10, 161.65 (N-C=O), 167.21 (O-C=O). IR (KBr) in cm^-1: 1253 (C-O-C), 1340, 1387, 1436, 1472 (C=N), 1598 (C=C), 1677 (N-C=O), 1715 (O-C=O), 2951 (=CH). MS-ESI: m/z 385 [M+H]⁺.HRMS (ESI):m/z, (M+H)⁺ calculated for C₂₄H₂₀N₂O₃: 385.1552: found 385.1559.

(E)-methyl 2- ((2-methyl quinazolin-4-yloxy) methyl) -3-(naphthalen-1-yl) acrylate (5e): ¹H NMR (CDCl₃, 300 MHz): d 2.52 (s, 3H, CH₃), 3.90 (s, 3H, O-CH₃), 5.34 (s, 2H, O-CH₂), 7.34-7.44 (m, 2H, H_Ar), 7.46-7.51 (d, 3H, J = 7.18 Hz, H_Ar), 7.69-7.85 (m, 4H, H_Ar), 7.90-7.95 (t, 1H, J = 5.67 Hz, H_Ar), 7.99-8.05 (d, 1H, J = 8.12 Hz, H_Ar), 8.59 (s, 1H, H_Ar). ¹³C NMR (CDCl₃, 75 MHz): d 26.17 (CH₃), 52.37 (O-CH₃), 61.94 (O-CH₂), 114.50, 123.43, 124.45, 125.27, 125.96, 126.37, 126.73, 126.86, 128.59, 128.78, 129.31, 129.74, 131.46, 131.71, 133.37, 138.58, 144.21, 151.36, 163.63 (O-C=O), 165.87 (N-C=N), 167.13 (O-C=N). IR (KBr) in cm^-1: 1232 (C-O-C), 1370, 1493 (C=N), 1574, 1622 (C=C), 1711 (O-C=O), 2926 (C=CH), 3055 (Ar CH). MS-ESI: m/z 385 [M+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₄H₂₁N₂O₃: 385.1552; found 385.1561.

 (E)-ethyl 3- (4-bromo phenyl) -2-((2-methyl-4-oxo quinazolin -3 (4H)- yl) methyl) acrylate (4f):¹H NMR (CDCl₃, 300 MHz): d 1.15-1.22 (t, 3H, J = 7.18 Hz, CH₃) 2.53 (s, 3H, CH₃), 4.09-4.18 (q, 2H, J = 7.18 Hz, CH₂), 5.14 (s, 2H, N-CH₂), 7.23-7.26 (d, 2H, J = 8.50 Hz, H_Ar), 7.34-7.42 (q, 3H, J = 8.31 Hz, H_Ar), 7.47-7.50 (d, 1H, J = 8.12 Hz, H_Ar), 7.62-7.67 (t, 1H, J = 7.18 Hz, H_Ar), 7.76 (s, 1H, C=CH), 8.07-8.10 (d, 1H, J = 7.93 Hz, H_Ar). ¹³C NMR (CDCl₃, 75 MHz): d 13.99 (CH₃), 23.36 (CH₃), 41.80 (CH₂), 61.26 (N-CH₂), 120.26, 126.28, 126.52, 126.74, 128.76, 130.07, 131.67, 133.21, 134.11, 140.86, 146.97, 154.27, 159.98, 161.92 (N-C=O), 165.76 (O-C=O). IR (KBr) in cm^-1: 1319 (C-O-C), 1383, 1474 (C=N), 1591(C=C), 1674 (N-C=O), 1716 (O-C=O), 2965, 2989 (=CH). MS-ESI: m/z 427 [M+H]⁺, 429 [M+2+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₁H₂₀N₂O₃Br: 427.0657; found 427.0653.

(E)-ethyl 3-(4-bromo phenyl) -2 - ((2-methyl quinazolin-4-yloxy) methyl) acrylate (5f): ¹H NMR (CDCl₃, 300 MHz): d 1.29 (t, 3H, J = 6.79 Hz, CH₃) 2.68 (s, 3H, CH₃), 4.27-4.34 (q, 2H, J = 6.79 Hz, CH₂), 5.36 (s, 2H, O-CH₂), 7.32-7.37 (d, 2H, J = 8.31 Hz, H_Ar), 7.41-7.47 (dt, 1H, J = 1.51 Hz, J = 8.31 Hz,H_Ar), 7.48-7.52 (d, 2H, J = 9.06 Hz, H_Ar), 7.73-7.79 (dt, 1H, J = 1.51 Hz, J = 8.31 Hz, H_Ar), 7.81-7.85 (d, 1H, J = 7.55 Hz, H_Ar), 7.95 (s, 1H, C=CH), 8.03-8.08 (d, 1H, J = 8.31 Hz, H_Ar). ¹³C NMR (CDCl₃, 75 MHz): d 14.45 (CH₃), 26.38 (CH₃), 61.22 (CH₂), 61.46 (CH₂), 114.57, 123.35, 124.17, 126.04, 127.25, 128.26, 131.06, 132.08, 133.39, 143.93, 151.66, 163.56 (O-C=O), 165.84 (O-C=N), 166.42 (N-C=N). IR (KBr) in cm^-1: 1248 (C-O-C), 1322, 1366, 1420, 1491 (C=N), 1576 (C=C), 1637, 1720 (O-C=O), 2921, 2973 (=CH). MS-ESI: m/z 427 [M+H]⁺. HRMS (ESI): m/z, (M+H)⁺ calculated for C₂₁H₂₀N₂O₃Br: 427.0657; found 427.0663.

RESULTS AND DISCUSSION: Baylis-Hillman bromides (cinnamyl bromides) 1a-j used in the reactions were synthesized according to the literature procedure ⁵¹ Scheme 1. Quinazolin-4(3H)-one (2a) and 2-methylquinazolin-4(3H)-one (2b) were prepared based on the earlier procedure ^{52, 53} from anthranilic acid and formamide, acetamide respectively in microwave.

SCHEME 1: SYNTHESIS OF CINNAMYL BROMIDES FROM BAYLIS-HILLMAN ADDUCTS

The Baylis-Hillman derived 3-cinnamyl substituted quinazolinone derivatives were prepared by the reaction between Baylis-Hillman bromides 1a-j and quinazolin-4(3H)-one (2a), in presence of a base. During the optimization studies, the reaction was carried out with cinnamyl bromide 1a with quinazolinone 2a in different bases such as NaH, KOH, K₂CO₃, in DMF, NaOMe in MeOH, and in NEt₃. It was observed that with K₂CO₃, in DMF the desired 3-cinnamyl quinazolinone derivative 3a was obtained at ambient temperature in 1h with 95 % yield Scheme 2. In order to evaluate the generality of this method, several analogues of 3-cinnamyl substituted quinazolinone derivatives 3b-j were synthesized by the reaction of quinazolin-4(3H)-one (2a) with different Baylis-Hillman cinnamyl bromides 1b-j Scheme 2. The reactions proceeded very efficiently with good yields in less reaction time (40–60 min) Table 1. Withdrawing substituted Baylis-Hillman bromides produce the corresponding 3-cinnamyl substituted quinazolinone derivatives in less reaction time with high yields compared to compounds with donating substituent. The structures of 3a-j were firmly established by well-defined ¹H-NMR, ¹³C-NMR, IR, and HRMS. As the ester-substituted Baylis-Hillman bromides are with a Z-stereochemistry, they produced 3-cinnamyl substituted quinazolinone derivatives 3a-h with E-stereochemistry exclusively which is confirmed by the crystal structure of 3c.

SCHEME 2: SYNTHESIS OF 3-CINNAMYL SUBSTITUTED QUINAZOLINONE DERIVATIVES

Single-Crystal X-ray Diffraction Analysis of Compound 3c: C₂₀H₁₅F₃N₂O₃. M = 388.34, monoclinic, space group P2₁/c, a = 13.063(4) Å, b = 9.952(3) Å, c = 14.528(5) Å, b = 107.551(5)°, V = 1800.8(10) ų, Z = 4, D_c = 1.432 Mg m-3,  l= 0.71073Å, μ(Mo Ka ) = 0.118mm-1, F000 = 800, T = 294(2) K. Total number of measured reflections is 14269. Final refinement to convergence on F² gave R= 0.0385 (2381 obs. data only) and Rw = 0.1080, GOF = 1.058. Intensity data were measured on Bruker Smart Apex with a CCD area detector. CCDC 885544 contains supplementary Crystallographic data for the structure.

FIG. 2: ORTEP REPRESENTATION OF COMPOUND 3c WITH THERMAL DISPLACEMENT ELLIPSOIDS AT THE 30% PROBABILITY

The cyano substituted Baylis-Hillman bromides are with a mixture of E and Z-isomers in which E-isomer as major product based on earlier reports; they produced 3-cinnamyl substituted quinazolinone derivatives 3i-j with Z and E-isomers. These compounds were recrystallized with a mixture of hexane and ethyl acetate (3:1) to produce Z-isomer exclusively. It was confirmed by the crystal structure obtained for compound 3i. Hence the compounds used for bio-evaluation are with E-stereochemistry for compounds 3a-h and with Z- stereochemistry for compounds 3i-j.

Single-Crystal X-ray Diffraction Analysis of Compound 3i: C₁₈H₁₂N₄O₃. M = 332.32, monoclinic, space group P2₁/c, a = 15.5743(15) Å, b = 8.5548(9) Å, c = 12.3161(12) Å, b = 104.611 (2)°, V = 1587.9(3) ų, Z = 4, D_c = 1.390 Mg m-3, l= 0.71073Å, μ (Mo Ka) = 0.098mm^-1, F000 = 688, T = 294(2) K. Total number of measured reflections is 14757. Final refinement to convergence on F² gave R= 0.0368 (2434 obs. data only) and Rw = 0.0998, GOF = 1.024. Intensity data were measured on Bruker Smart Apex with CCD area detector. CCDC 885543 contains supplementary Crystallographic data for the structure.

FIG. 3: ORTEP REPRESENTATION OF COMPOUND 3i WITH THERMAL DISPLACEMENT ELLIPSOIDS AT THE 30% PROBABILITY

TABLE 1: VARIOUS QUINAZOLINONE DERIVATIVES SYNTHESIZED

^aisolated yields, ^bisolated yields after recrystallization

To demonstrate the general utility of the method, 2-methylquinazolin-4(3H)-one, different Baylis-Hillman derived cinnamyl 2-methylquinazolin-4(3H)-one derivatives were prepared Scheme 3 Table 2. Baylis-Hillman bromide esters 1a-f and 2-methylquinazolin-4(3H)-one (2b), were reacted in the presence of a base K₂CO₃ in DMF at room temperature and the reactions were completed within 1 h. TLC monitoring of the reaction shows complete consumption of the reactants and appearance of two new products. The reaction was quenched with water and the obtained solid was filtered, washed again with water and dried. The two new products were separated by column chromatography and fully characterized by IR, ¹HNMR, ¹³C-NMR, and HRMS and shown in Table 2. Amongst the two products, the more polar products 4a-f were identified as 3-N-cinnamyl substituted 2-methyl quinazolin4-one compounds and the less polar products 5a-f were identified as4-O-cinnamyl substituted 2-methylquinazoline compounds. These indicate alkylation of 2-methyl quinazolin-4(3H)-one produces two isomers, one with N-substitution and another with O-substitution. The percentage formation of N-isomer is almost equal to O-isomer identified from the isolated yields formed. The formation of O-isomer may be due to the steric effect and electronic factor of methyl substitution at the 2-position with the cinnamyl bromide during alkylation. The two isomers formed in the reaction were confirmed by X-ray crystallography.

SCHEME 3: SYNTHESIS OF CINNAMYL SUBSTITUTED 2-METHYL QUINAZOLINONE DERIVATIVES

TABLE 2: VARIOUS 2-METHYL QUINAZOLINE AND QUINAZOLINONE DERIVATIVES SYNTHESIZED

^aisolated yields

Single-Crystal X-ray Diffraction Analysis of Compound 4f:C₂₁H₁₉BrN₂O₃. M = 427.29, triclinic, space group P^-1, a = 8.7956(6)Å, b = 10.4379(7)Å, c = 11.0152(7)Å, α = 79.103(1) °,b = 71.464(1)°, γ = 84.907(1) °, V = 941.08(11)ų, Z = 2, D_c = 1.508 Mg m-3, l= 0.71073Å, μ(Mo Ka ) = 2.208 mm^-1, F000 = 436, T = 294(2) K. Total number of measured reflections is 9099. Final refinement to convergence on F² gave R= 0.0267 (3001 obs. data only) and Rw = 0.0681, GOF = 1.054. Intensity data were measured on Bruker Smart Apex with CCD area detector. CCDC 826451 contains supplementary Crystallographic data for the structure.

FIG. 4: ORTEP REPRESENTATION OF COMPOUND 4f WITH THERMAL DISPLACEMENT ELLIPSOIDS AT THE 30% PROBABILITY

Single-Crystal X-ray Diffraction Analysis of Compound 5e: C₂₄H₂₀N₂O₃. M = 384.42, monoclinic, space group P2₁/n, a = 12.0764(12) Å, b = 8.6922(9) Å, c = 18.7930(19) Å, b = 100.867(2)°, V = 1937.3(3) ų, Z = 4, D_c = 1.318 Mg m-3, l= 0.71073Å, μ (Mo Ka ) = 0.088mm-1, F000 = 808, T = 294(2) K. Total number of measured reflections is 18042. Final refinement to convergence on F² gave R= 0.0358 (3071 obs. data only) and Rw = 0.0978, GOF = 1.051. Intensity data were measured on Bruker Smart Apex with CCD area detector. CCDC 885542 contains supplementary Crystallographic data for the structure.

FIG. 5: ORTEP REPRESENTATION OF COMPOUND 5e WITH THERMAL DISPLACEMENT ELLIPSOIDS AT THE 30% PROBABILITY

These data can be obtained free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html[or from the Cambridge Crystallographic Data Centre (CCDC), 12 Union Road, Cambridge CB2 1EZ, UK; Fax: +44(0) 1223 336 033; email: deposit@ccdc.cam.ac.uk].

Biological Evaluation: All the synthesized compounds are screened for their antimicrobial activity by both dilution method recommended by the National Committee for Clinical Laboratory (NCCL) standards ⁵⁴. The minimum inhibitory concentrations (MIC) of various substituted quinazolinone and methyl quinazolinone derivatives were tested against three representative Gram-positive organisms viz. Bacillus subtilis, Staphylococcus aureus, Staphylo coccus epidermidis and three Gram-negative organisms viz. Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumonia against standards penicillin and streptomycin. The minimum inhibitory concentration (MIC) values are presented in Table 3. It has been observed that the test compounds exhibited moderate antibacterial activity, against all the tested organisms. The compound 3a, without any substituent at the aryl group exhibited good antibacterial activity especially on S. epidermidis (gram positive). Replacement of hydrogen at the ortho position of the aryl group by CF₃ (3c) and the para position of the aryl group by fluoro (3g) exhibited significant activity on both gram-positive (S. epidermidis) and gram-negative (K. pneumonia) organisms. Baylis-Hillman derived 3-cinnamyl substituted quinazolinone derivatives with ester group 3a-h are more active compared to cyano substituted Baylis- Hillman derived 3-cinnamyl substituted quinazolinone derivatives 3i-j.N-cinnamyl substituted 2-methylquinazoline compounds 4a-fare showing better antibacterial activity compared to the O-cinnamyl substituted 2-methyl quinazolinone compounds 5a-f. 4a and 4c are showing moderate antibacterial activity. Hence the compounds with fluorine, CF₃ substituents have significant antibacterial activity compared to the other compounds.

TABLE 3: ANTIBACTERIAL ACTIVITY OF QUINAZOLINONE AND METHYL QUINAZOLINONE DERIVATIVES

All the compounds are also screened for their antifungal activity against Yeast and Filamentous fungi viz. Candida albicans, Candida rugosa, Saccharomyces cerevisiae, Aspergillus niger, Rhizopus oryzae concerning standard Amphotericin B (50 µg) by Agar well diffusion method ⁵⁵. Zone of inhibition (mm) was determined for all the compounds. The screening results indicate that all the compounds are showed moderate antifungal activity against C. albicans and inactive on the remaining organisms Table 4. All the compounds exhibited interesting antifungal activity on C. albicans microorganism, however with a degree of variation. Compounds 3a and 4f exhibited good antifungal activity compared to the other compounds.

TABLE 4: ANTIFUNGAL ACTIVITY OF QUINAZOLINONE AND METHYL QUINAZOLINONE DERIVATIVES

CONCLUSION: We developed a new simple and efficient method for the synthesis of a series of new Baylis-Hillman derived N-cinnamyl substituted quinazolinone and 2-methylquinazolinone derivatives, and O-cinnamyl substituted 2-methyl quinazoline derivatives in good yields. All the synthesized compounds were evaluated for their antimicrobial activity. All compounds are found to be active against all bacterial test strain. Amongst ester substituted compounds, (3a, 3c, 3g and 4a, 4c) shows good antibacterial activity in comparison to cyano substitution. Similarly, compounds with fluorine substituents are active on both gram-positive (S. epidermidis) and gram-negative (K. pneumoniae) organisms. All the compounds show moderate anti-fungal activity against C. albicans. Compound 3a, 4f shows high antifungal activity than the other compounds.

ACKNOWLEDGEMENT: The authors thank Director, Indian Institute of Chemical Technology, for the encouragement. Authors at IICT acknowledge ORIGIN Project-CSC-0108for financial assistance. C.L.D, Y.R and U.K.O.M thank the Council of Scientific and Industrial Research, New Delhi for Research Fellowship.

CONFLICT OF INTEREST: Nil

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    Chebrolu LD, Jhansi UKOM, Vadla R, Balasubramanian S, Vidya JR and Upadhyayula SNM: Synthesis, characterization and antimicrobial activity of some new baylis-hillman derived cinnamyl substituted quinazolinone derivatives. Int J Pharm Sci & Res 2014; 5(9): 3679-91. doi: 10.13040/IJPSR.0975-8232.5(9).3679-91.

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