Diastereospecific intramolecular Ullmann couplings: unique chiral auxiliary for the preparation of 3,3'-disubstituted MeO-BIPHEP derivatives.
[reaction: see text] A chiral auxiliary is described that provides only one diastereomer during intramolecular Ullmann couplings. Treatment of five Ullmann coupling precursors with Cu powder in DMF at 115 degrees C provides 2,2',3,3',6,6'-hexasubstituted 1,1'-biphenyls as single diastereomers in yields ranging from 66% to 91%.
Gorobets
E
E
Department of Chemistry, University of Calgary, Calgary, AB, Canada.
McDonald
R
R
Keay
B A
BA