Investigation of the Effects of the Structure and Chelate Size of Bis-oxazoline Ligands in the Asymmetric Copper-Catalyzed Cyclopropanation of Olefins: Design of a New Class of Ligands
作者:Ashutosh V. Bedekar、Elise B. Koroleva、Pher G. Andersson
DOI:10.1021/jo962021a
日期:1997.4.1
D-tartaric acid, two sets of ligands (6b-e and 7a,b) were synthesized and evaluated in the copper-catalyzed cyclopropanation of olefins. The comparison of benzyl and isopropyl derivatives of these ligands with previously reported five- and six-membered bis-oxazolines clearly indicates the beneficiary effect of the larger chelate size and the chiral tether of the tartrate-derived ligand. The effect of the different
A formal synthesis of (±)-aristeromycin starting from the imino Diels-Alder cycloadduct 3a has been achieved with high overall yield. A novel method for the in situ preparation of N-sulfonylimines is reported.