Rearrangement of ammonium ylides produced by intramolecular reaction of catalytically generated metal carbenoids. Part 1. Synthesis of cyclic amines

Abstract

Cyclic amines have been prepared in good yield by [2,3]-rearrangement of ammonium ylides produced by intramolecular reaction of copper carbenoids tethered to allylic amines. Copper(II) acetylacetonate is the optimum catalyst for carbenoid/ylide generation from the diazo ketone precursor, and reactions must be performed at elevated temperatures in order to obtain reasonable reaction rates and high yields. The reaction has been used to prepare five- to eight-membered cyclic amines. In cases where the substrate possesses a substituent on the tether connecting the diazo group to the allylic amine, tandem ylide formation and rearrangement delivers a high yield of the expected 2,5-dialkylpyrrolidinone or 2,6-dialkylpiperidinone, but low levels of diastereocontrol are obtained.