Studies on Some 1-Substituted Heterocyclic Isoquinoline Derivatives by Bischler-Napieralski Reaction. IV

Syntheses of Isoquinoline Derivatives of Furan Series

Abstract

Syntheses of isoquinolines substituted with furan ring in 1-position or with 5-nitro- or -bromo-furan ring in the 2-position was attempted. 2-Furoyl chlorides (III) substituted with 5-nitro or 5-bromo group, and 2-furoylazide (VIa), 2-(5-nitro) furoylazide (VIb), 2-(5-bromo) furoylazide (VIc) were prepared from furfural, and α-methyl-β-(3, 4-methylenedioxyphenyl)-β-methoxyethylamine (VIII) was prepared from safrol by the usual process. Condensation of this amine (VIII) with the chlorides (III) and azides (VI) afforded the corresponding acid amides (IX). Bischler-Napieralski condensation of these acid amides successfully afforded isoquinolines as free bases; 1-(2-furyl)-(Xa: R=H), 1-(5-nitro-2-furyl)-(Xb: R=NO₂), and 1-(5-bromo-2-furyl)-3-methyl-6, 7-methylenedioxyisoquinoline (Xc: R=Br).