Nucleophilic napththalene dearomatization of N-alkyl-N-benzyl(dinaphthyl)phosphinamides. Application to the synthesis of gamma-(N-alkylamino) (dihydronaphthalenyl)phosphinic acids

摘要

Lithiation of N-alkyl-N-benzyl(dinaphthyl)phosphinamides with s-BuLi at -90 degreesC in THF promoted the dearomatization of one naphthalene ring through anionic cyclization. The intermediate lithium compounds were trapped with MeOH, MeI and allyl bromide affording benzo[e]-1-phosphaisoindoles with excellent stereoselectivities. Acid hydrolysis of the P-N link-age allowed to obtain gamma-(N-alkylamino)phosphinic acids containing a dihydronaphthalene system. This structural fragment proved to be an element of conformational restriction. [References: 26]