| 摘要 |
compounds of formula I <IMAGE> wherein R1 represents a C1-8 alkyl, C2-8 alkenyl, C2-8 alkynyl, C3-8 cycloalkyl(C1-8)alkyl, C1-8 hydroxyalkyl, C1-8 alkylthio, phenyl or substituted phenyl; R3 represents a C1-8 alkyl, C2-8 alkenyl, C2-8 alkynyl, CO2(C1-8)alkyl, CO2(C2-8) alkenyl, C1-8 alkylthio, (C1-2)alkyl CO2(C1-8) alkyl or C1-8 aldehydroalkyl where the aldehyde function is protected by a suitable protecting group (for example, an acetal such as a dimethyl acetal); R4 represents a hydrogen atom, C1-8 alkyl or C2-8 alkenyl; Z represents a group (CH2)n or a branched alkyl chain; n is 1 to 8; and each of a, b and c is independently a single or a double bond; can be prepared relatively easily and in good xxx at room temperature by reacting a compound of general formula II <IMAGE> wherein R2, R3, R4, Z, a, b and c are as define din general formula I; with a compound of general formula III CHI2R1 (III) wherein R1 is as defined in general formula I; in the presence of metal ions such as chromium (II) ions. The sever conditions of the Wittig reaction can therefore be avoided. Compounds of formula I are useful intermediates in the synthesis of mevinic acids, which are potent inhibitors of HMG-CoA reductase and which are useful in the treatment of hypocholesterolaemia an hyperlipidaemia. |
