Reduction of 4‐arylidene‐1,3‐(2H,4H)isoquinolinediones

Abstract

Catalytic hydrogenation of some 4‐arylidene‐1,3‐(2H,4H)isoquinolinediones (1) afforded the corresponding 4‐arylmethyl‐1,3‐(2H,4H)isoquinolinediones (2), but reduction of 1 by sodium borohydride gave 4‐arylmethyl‐1(2H)isoquinolones (isocarbostyrils, 3). Compounds of type 1 studied had aryl substituents phenyl, 3,4‐dimethoxyphenyl, 3,4‐methyleneoxyphenyl and 2‐furyl. In one example of sodium borohydride reduction of an N‐methylisoquinolinedione derivative (1) the heterocylic ring was opened, and 2‐(1‐hydroxymethyl‐2‐phenylethenyl)‐N‐methylbenzamide (4) was obtained from 4‐benzylidene‐2‐methyl‐1,3‐(2H,4H)isoquinolinedione.