Application of the PMC Protecting Group in the Efficient Synthesis of 4,4‐Disubstituted Piperidines
摘要:
An efficient synthesis of the 4,4-disubstituted piperidine scaffold 1 was accomplished by treating the PMC N-protected alpha,beta-unsaturated ethyl cyanoacetate 9 with various Grignard reagents (R1MgX). Subsequent heating at 190 degrees C in a strong base provided carboxylic acids 12-20b in good yield. The PMC group was easily removed at room temperature with 33% HBr in acetic acid.