Improved E-selectivity in the Wittig reaction of stabilized ylides with alpha-alkoxyaldehydes and sugar lactols.
[reaction: see text]. The Wittig reactions of alpha-alkoxyaldehydes and sugar lactols with stabilized ylides such as (alkoxycarbonylmethylene)triphenylphosphoranes typically proceed with low E-selectivities. However, we have discovered that the reaction of such aldehydes with (methoxycarbonylmethylene)tributylphosphorane in toluene in the presence of catalytic amounts of benzoic acid proceeds to give the E-alpha,beta-unsaturated esters with high selectivities and in high yields.
Harcken
C
C
Department of Chemistry and Biochemistry, The University of Texas, Austin, Texas 78712, USA.
Martin
S F
SF
D000447:Aldehydes / Q000737:chemistry*; D007202:Indicators and Reagents; D007783:Lactones / Q000737:chemistry*; D009005:Monosaccharides / Q000737:chemistry*; D010753:Phosphoranes / Q000737:chemistry*; D013237:Stereoisomerism
D000447:Aldehydes; D007202:Indicators and Reagents; D007783:Lactones; D009005:Monosaccharides; D010753:Phosphoranes