Studies on the syntheses of heterocyclic compounds. Part 724. Total syntheses of the quinazolinone alkaloids glycorine, glomerine, homoglomerine, crysogine, and euxylophoricines A and C

Abstract

Treatment of the sulphinamide anhydride 1-methyl-3,2,1-benzoxathiazin-4(1H)-one S-oxide (5), derived from N-methylanthranilic acid (1), with amides (9)–(11) gave glycorine (14), glomerine (15), and homoglomerine (16), respectively. Reaction of the N-unsubstituted sulphinamide anhydride (6) with O-benzyl-lactamide (13), followed by debenzylation of the resulting 2-(1-benzyloxyethyl)quinazolin-4(3H)-one (17) yielded crysogine (18). Condensation of the sulphinamide anhydrides (7) and (8), prepared from the corresponding dimethoxy- and methyl-enedioxy-anthranilic acid derivatives (3) and (4), with 3,4-dihydro-β-carboline (19) furnished euxylophoricines A (20) and C (21). 5,11-Dimethyldibenzo[b,f][1,5]diazocine-6,12(5H,11H)-dione (22) was obtained from the N-methylsulphinamide anhydride (5).