Provided by: American Chemical Society
Date Added: Nov 2004
Aza-Diels-Alder reaction between 2-[(R)-1-phenylethyl] iminoethanoate (1) and cyclopentadiene using the biphasic solvent system (TMSCl-CH3OH/toluene) gave (1S, 3S, 4R)-2-[(R)-1- phenylethyl]-2-aza-bicyclo [2.2.1] hept-5-ene-3-carboxylates (3a) in 32% isolated yield. The present method is advantageous for the large-scale synthesis, because the reported methods required harmful and expensive fluorinated chemicals, methyl analogue 3a was practically isolated as a crystalline solid, and the reaction was conducted with very little observable exotherm. In addition, the absolute configurations of the other three diastereomers 2, 4, and 5 were unambiguously determined.