Highly Enantioselective Diethylzinc Addition to Imines Employing Readily Available <i>N</i>-Monosubstituted Amino Alcohols
作者:Hai-Le Zhang、Xiao-Mei Zhang、Liu-Zhu Gong、Ai-Qiao Mi、Xin Cui、Yao-Zhong Jiang、Michael C. K. Choi、Albert S. C. Chan
DOI:10.1021/ol025728u
日期:2002.4.1
easily accessible chiral ligand 3c, which promoted diethylzinc addition to imines with 96-98% ee, has been found by finely screening N,N-disubstituted and N-monosubstituted aminoalcohols. N-monosubstituted aminoalcohols, on average, gave slightly higher enantioselectivities than their N,N-disubstituted analogues. These results imply that the restricted and rigid structure of aminoalcohol is not the absolute
Modification of (1R,2S)-1,2-Diphenyl-2-aminoethanol for the Highly Enantioselective, Asymmetric Alkylation ofN-Diphenylphosphinoyl Arylimines with Dialkylzinc
Experimental studies on the modification of (1R,2S)-1,2-diphenyl-2-aminoethanol, which is used to promote the alkylation of N-diphenylphosphinoyl benzalimine with diethylzinc, revealed that N-monosubstituted amino alcohols exhibited higher enantioselectivities than their N,N-disubstituted counterparts and imino alcohols. Application of the optimal chiral ligand 3c to activate the reaction of N-diphenylphosphinoyl