Highly diastereoselective synthesis of 2-azabicyclo2.2.1hept-5-ene derivatives : bronsted acid catalized aza-diels-alder reaction between cyclopentadiene and imino-acetates with two chiral auxiliaries

摘要

The cycloaddition between protonated glyoxylate imines possessing twochiral auxiliaries, N-(S)- or N-(R)-1-phenylethyl and (-)-8-phenylmenthyl or (+)-8-phenylneomenthyl, and cyclopentadiene is described. The absolute configuration of alladducts formed was unequivocally assigned through NMR, specific optical rotation andX-ray data of appropriated derivatives. Experimental results confirm the highly exoselectivityfor these aza-Diels–Alder reactions, single adducts being obtained fromcombinations of (8PM)-(R-PEA) and (8PNM)-(S-PEA).