Studies on tertiary amine oxides. LI. Reactions of quinoline and isoquinoline N-oxides with propiolates and methacrylonitrile.

Abstract

The 1, 3-dipolar cycloaddition between quinoline N-oxide (I) and methyl propiolate progressed in the presence of acetic anhydride or hydroquinone to afford methyl α-formyl-2-quinolineacetate (IIa). The reaction with ethyl propiolate in the presence of hydroquinone gave the corresponding ethyl ester (IIb). The reaction of I with methacrylonitrile in the presence of hydroquinone produced cyanohydrin of 2-acetonylquinoline (VIII) or 2-acetonylquinoline (IX) and 2-cyanoquinoline (X). Isoquinoline N-oxide (XI) was less reactive and resisted the reaction with propiolates, but reacted with methacrylonitrile in the presence of hydroquinone to give 1-acetonyl-isoquinoline (XII), 1-cyanoisoquinoline (XIII) and isoquinoline.