Highly enantioselective Friedel-Crafts reaction of aromatic amines with ethyl glyoxylate catalyzed by chiral titanium(IV) complexes: practical synthesis of aminomandelic acid derivatives.
The asymmetric Friedel-Crafts reaction of a variety of N,N-dialkylanilines with ethyl glyoxylate has been achieved by the catalysis of titanium complexes of BINOL derivatives to give corresponding ethyl esters of p-N,N-dialkylaminomandelic acids in high yields (85-99%) and good to excellent enantioselectivities (80-96.6% ee) under the optimized reaction conditions, which has added a new catalyst for this class of reactions. The reaction could also be carried out at a reduced catalyst loading (1 mol %) in gram scale, which provided a practical synthesis of enantiopure aminomandelic acid derivatives.
Yuan
Yu
Y
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, P. R. China.
Wang
Xingwang
X
Li
Xin
X
Ding
Kuiling
K