Titanium(IV) chloride, zirconium(IV) chloride or boron trichloride and phosphine-promoted Baylis-Hillman reaction of aldehydes with alpha,beta-unsaturated ketone
M. Shi et al., Titanium(IV) chloride, zirconium(IV) chloride or boron trichloride and phosphine-promoted Baylis-Hillman reaction of aldehydes with alpha,beta-unsaturated ketone, J CHEM S P1, (4), 2001, pp. 390-393
In the Baylis-Hillman reaction of aldehydes with an alpha,beta -unsaturated
ketone, the chlorinated compound 1 was obtained as the major product using
tributylphosphine as a Lewis base in the presence of titanium(IV) chloride
, zirconium(IV) chloride or boron trichloride in dichloromethane at < -20 d
egreesC. A plausible reaction mechanism has been proposed. Using (R)-(+)-2,
2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP) as a chiral Lewis base, 1
0% ee could be achieved. We also found that, if the reaction was carried ou
t at room temperature, the dehydrated compound 3 was obtained as the major
product in the Z-configuration.