1,5-Stereocontrol in tin(IV) halide promoted reactions of 2-alkoxy-1-(2-tributylstannylethylidene)cyclohexanes with aldehydes

2-Methoxy- and 2-(p-methoxybenzyloxy)-1-(2-tributylstannylethylidene)cyclohexanes 22 and 23 were prepared from 2-methoxy- and 2-(p-methoxybenzyloxy)cyclohexanones 12 and 13. The allylstannane 22 was transmetallated stereoselectively with tin(IV) chloride at −78 °C to generate an allyltin trihalide, which reacted with aldehydes to give (Z)-(3-hydroxyalkylidene)-2-methoxycyclohexanes 24 with excellent 1,5-syn-stereocontrol. Similar reactions with aldehydes were observed for the 2-(p-methoxybenzyloxy) substituted allylstannane 23. The structure of the product 24f prepared from p-nitrobenzaldehyde was confirmed by an X-ray structure determination of its p-nitrobenzoate ester 27.