417705-77-2Relevant academic research and scientific papers
Rearrangement of ammonium ylides produced by intramolecular reaction of catalytically generated metal carbenoids. Part 1. Synthesis of cyclic amines
Clark,Hodgson,Goldsmith,Street
, p. 3312 - 3324 (2007/10/03)
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. Two new methods have been developed for the synthesis of diazo ketones containing a nucleophilic allylic amine substituent. The first method involves conjugate addition of allylic amines to unsaturated diazo ketones and is high yielding but of limited scope. The alternative general sequence involving nitrogen protection, α-diazo ketone formation, deprotection and allylation can be used to prepare the substrates required for intramolecular tandem ylide formation and rearrangement.
