Entrainer effect on photochirogenesis in near- and supercritical carbon dioxide: dramatic enhancement of enantioselectivity.
Diethyl ether added as an entrainer (cosolvent) to near- and supercritical CO2 significantly enhanced the enantioselectivity of photocyclization of 5,5-diphenyl-4-penten-1-ol sensitized by saccharide naphthalenedicarboxylate to give a cyclization product in enantiomeric excesses much larger than those obtained in conventional organic solvents, revealing the unique features of nc- and sc-CO2 as well as the critical role of entrainer clustering to the intervening diastereomeric exciplex pair.
Nishiyama
Yasuhiro
Y
Department of Applied Chemistry, Osaka University, Suita 565-0871, Japan.
Wada
Takehiko
T
Asaoka
Sadayuki
S
Mori
Tadashi
T
McCarty
Taylor A
TA
Kraut
Nadine D
ND
Bright
Frank V
FV
Inoue
Yoshihisa
Y