Other Reagents as Co-catalysts

We have found that in the presence of a catalytic amount of nitrophenol, the Lewis base triphenylphosphine can effectively promote the MBH reaetion of aldehydes with methyl vinyl ketone to give the corresponding normal MBH 

R = Ph, 4-CIPh, 4-N02Ph, 3-N02Ph, 2-N02Ph, 4-MePh, 4-MeOPh, 2,4-Cl2Ph, 4-FPh, 4-BiPh, 2-pyrldyl, PhCH2CH2 

As the remarkable rate aeeeleration under protic solvents sueh as water or methanol has been widely reported, Choo and Chong found that the MBH 

Ar = 4-N02Ph, 4-FPh, 2-N02Ph, 4-CIPh, 2-CIPh, 4-pyridyl, Ph, 2-OHPh, 4-MeOPh, 3,5-(MeO)2Ph 

Method A MeOH 0-47% Method B Octanol 18-100% R = 2-furyl, 4-MeOPh, 4-HOPh, 4-CNPh, 4-CF3Ph, 2-N02Ph, 4-N02Ph, 4-CIPh 

---