1-AMINO-1-HYDROXYMETHYLCYCLOBUTANE DERIVATIVES VIA INTRAMOLECULAR AMINATION OF NONCLASSICAL CYCLOPROPYLMETHYL CATION

Abstract

Bis(trichlorocetimidoyloxymethyl)cyclopropanes provide intramolecular amination products of intermediate cyclobutyl or cyclopropylmethyl carbenium ion when exposed to Lewis acid catalyst or thermal ionization. The ratio of the two amination products of cyclobutyl carbenium ion depends primarily on the substituent at the alkoxymethyl group of the substrate and can be altered by the solvent used and the ionization conditions. An oxazoline derivative forms as the major amination product in the case of unsubstituted bis(trichloroacetimidoyloxymethyl)cyclopropane or if the substrate contains isopropyl or alkoxymethyl substituents. The amination of cyclobutyl carbenium ion formed in situ proceeds with high diastereoselectivity leading to exclusive formation of trans-cyclobutane derivatives. The latter can be transformed to N-Boc-protected cyclobutane-based amino alcohols in high yields.