Stereoselective Synthesis of (2<i>E</i>,4<i>E</i>)- and (2<i>Z</i>,4<i>E</i>)-2,4-Alkadienoates by the Ester Enolate Claisen Rearrangement of (<i>E</i>)-1-Alkyl-3-trimethylsilyl-2-propenyl Glycolates Followed by the Peterson Reaction
The esterenolateClaisenrearrangement of (E)-1-alkyl-3-trimethylsilyl-2-propenyl glycolates gave (E)-erythro-2-hydroxy-3-trimethylsilyl-4-alkenoates with high diastereoselectivity, which were stereoselectively converted into (2E,4E)- and (2Z,4E)-2,4-alkadienoates by the Peterson reaction.
Wittig reactions, of stable phosphorous ylids, when carried out in presence of silicagel, in hexane, provide a fast, efficient and simple method to obtain α:β unsaturated compounds in high yields and high purity.
Synthesis of Methyl 2-[Bis(benzylthio)phosphoryl]acetate as a Novel Horner–Wadsworth–Emmons-Type Reagent and Its Application to the Diastereodivergent Synthesis of (E)- and (Z)-α,β-Unsaturated Esters
Methyl 2-[bis(benzylthio)phosphoryl]acetate has proven to be an efficient Horner–Wadsworth–Emmons (HWE)-type reagent for the diastereodivergent synthesis of (E)- and (Z)-α,β-unsaturated esters. Under the conditions of excess NaHMDS relative to the HWE-type reagent, the HWE-type reactions of methyl 2-[bis(benzylthio)phosphoryl]acetate with various aldehydes afforded the corresponding α,β-unsaturated
Convenient Preparations of (Diphenylphosphono)acetic Acid Esters and the Comparison of the <i>Z</i>-Selectivities of Their Horner−Wadsworth−Emmons Reaction with Aldehydes Depending on the Ester Moiety
作者:Kaori Ando
DOI:10.1021/jo9907181
日期:1999.10.1
Direct synthesis of Z-unsaturated esters. A useful modification of the horner-emmons olefination.