Ring transformation of 1-[(1,2,4-oxadiazol-3-yl)methyl]isoquinolines into 2-acylaminopyrazolo[5,1-a]isoquinolines

Abstract

Selective reduction of 1-[(1,2,4-oxadiazol-3-yl)methyl]-3,4-dihydroisoquinolines (8) gives the tetrahydro derivatives (12) which readily isomerize to 2-acylaminopyrazolo[5,1-a]isoquinolines (13). Compounds (13) were also obtained by reaction of the isoquinolinylacetamide oxime (11) with esters (6). A comparision of ring transformations in the series of compounds (8) and (12) indicated that both followed the same mechanism. This provided further support to the proposed^1a extension of the Type-2 Boulton–Katritzky scheme.