Mild and highly enantioselective vinylogous aldol reaction of Brassard's diene with aromatic aldehydes by combined Lewis acid catalyst.
The combined Lewis acid catalytic system, generated from (R)-1,1'-bi-2-naphthol [(R)-BINOL], Ti(O-i-Pr)(4), H(2)O, and lithium chloride, effectively catalyzed the enantioselective vinylogous aldol reaction of Brassard's diene with aromatic aldehydes affording the (Z)-delta-hydroxyl-alpha,beta-unsaturated esters exclusively in good yields with excellent enantioselectivities (90-99% ee) under mild conditions. A Lewis acid-Lewis acid bifunctional working model was proposed for the catalytic process based on some control experiments.
Wang
Guowei
G
State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116012, People's Republic of China.
Zhao
Jinfeng
J
Zhou
Yuhan
Y
Wang
Baomin
B
Qu
Jingping
J