| 摘要 |
PURPOSE:To prepare the titled compound in high yield and steric selectivity, by reacting a specific propargyl alcohol with a Grignard reagent in the presence of a catalytic amount of dicyclopentadienyl-dichlorotitanium. CONSTITUTION:A propargyl alcohol of formulaI(R<1> and R<2> are H or lower alkyl; R<3> is alkyl or aryl which may have substituent group inert to the reaction), e.g. the compound of formula II or formula III is made to react with a Grignard reagent of formula RMgX (R is lower alkyl; X is Cl, Br or I) in the presence of a catalytic amount of the compound of formula CP2TiCl2 (Cp is cyclopentadienyl group or its derivative). A tri-substituted olefin such as nerol or (E,Z)- farnesol, etc. can be prepared by reacting the above reaction product with e.g. a methylation reagent, etc. The method is useful for the selective synthesis of gamma,gamma'-di-substituted-2-alken-1-ols useful as a natural product or its intermediate. |
