Unique synthetic utility of BF(3).OEt(2) in the highly diastereoselective reduction of hydroxy carbonyl and dicarbonyl substrates
A new aspect of commonly used BF(3).OEt(2) has been illuminated by successfully demonstrating the unique but highly stereoselective reactions of hydroxy carbonyl and dicarbonyl substrates. For example, treatment of gamma-hydroxy ketone 1c with BF(3).OEt(2)/Bu(3)SnH in CH(2)Cl(2) at -78 to -40 degrees C afforded the corresponding 1, 4-diol 2c with virtually complete diastereoselection, while use of TiCl(4) as a Lewis acid under similar reaction conditions caused a total lack of diol yield and selectivity (17%; 2c/3c = 1.2:1), accompanied by a significant formation of 2,3-disubstituted tetrahydrofuran 4 (44%).
Ooi
T
Departments of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan, and Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
Uraguchi
D
Morikawa
J
Maruoka
K