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Abstract: A series of 6,8-dibromo-3-phenyl-2-substituted quinazolin-4-(3H)ones 5(a-f) have been synthesized from 6,8-dibromo-3-phenyl-2-methyl-quinazolin-4-(3H)one (4) with substituted aromatic aldehydes in presence of glacial acetic acid and concentrated sulphuric acid. The intermediate 6,8-dibromo-2-methyl benzoxazin-4-ones (3). All the newly synthesized compounds have been screened in Vivo for their antihypertensive activity. Compounds 5^sub a^, 5^sub b^, 5^sub e^ and 5^sub f^ were found to be potent members of this series; compound 5^sub a^ has exhibited better antihypertensive activity than the standard drug. The structures of the new compounds were established on the basis of their IR, ^sup 1^HNMR and Mass spectral studies.
Keywords: Anthranilic acid, Acetic anhydride, Quinazoline, Antihypertensive.
INTRODUCTION:
Quinazolinones have been found to exhibit diverse pharmacological activities such as antihypertensive1, anthemintic2, anti-inflamatory3, antitubercular4, anticonvulsant5, hypoglycemic6, antibacterial7-8, and anti-HIV9 Hypertension is still a dangerous disease affecting millions of people all over world. In view of this an attempt has been made to explore quinazolinones as potential antihypertensive agents.
In the present investigation we have reported the synthesis and antihypertensive activity of title compounds 6,8-dibromo-3-phenyl-2-substituted styryl-quinazolin-4(3H) ones 5(a-f).(Scheme 1)
MATERIALS AND METHODS
The melting points were determined in open capillaries using melting point apparatus and are uncorrected. Purity of the compounds were checked by TLC on pre coated TLC plates having silica gel F28 as adsorbent using pet ether and ethyl acetate (8:2) as mobile phase. the spots were located using UV at 254nm. IR spectra were recorded in KBr on a Shimadzu FTIR 8400 spectrophotometer using KBr pellets techique. 1H NMR spectra were obtained on the AMX-400 liquid state spectrometer at 400 MHz in CDCl3
Mass spectrum were recorded on Shimadzu GCMS spectrometer 210.
Synthesis of 3, 5 dibromo anthranilic acid (2)
To a solution of 40g of anthranilic acid in 500ml of glacial acetic acid, 19ml of bromine was added at a temperature of 16°C. The resulting mixture was extracted with 1 L of water containing 50ml of concentrated HCl. 3,5- Dibromo anthranilic acid precipited out was filtered, washed with distilled water, dried and recrystallised from aqueous ethanol; M.P 225°C; yield 27.86%; Rf =0.13. IR: 686 (C-Br), 1679 (C = O), 3030 (CH of aromatic ring), 3083, 3363 (NH),1H NMR (CDCl3): 7.7-8.2 (s, 2H, Ar H), 6.5 (s, 2H, NH2).
Synthesis of 6, 8- dibromo-2-methyl-benzoxazin-4-one (3)
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