Novel tetracyclic spiropiperidines. II. Synthesis of 2‐aryl‐2,3‐dihydrospiro[benzofuran‐3,4′‐piperidines]

Abstract

Abstract A series of 2‐aryl‐2,3‐dihydropsiro[benzofuran‐3,4′‐piperidines] has been synthesized as potential psychotropic agents via an efficient intramolecular fluorine displacement reaction. Treatment of a key intermediate, 4‐cyano‐4‐(2‐fluorophenyl)‐1‐methylpiperidine ( 2 ), with a large excess of phenylmagnesium bromide in refluxing tetrahydrofuran led to some 2‐arylspiro[3 H ‐indole‐3,4′‐piperidine] derivatives, 10 and 11 , whose structures are elucidated on the basis of chemical and spectral evidence.