摘要:
                                The steric selectivity of the Horner-Emmons reaction between isovaleraldehyde and 3-carboethoxy-2-methyl-2-propenylphosphonates depends on the structure of the alkoxy substituents at the phosphorus atom.  The use of five- and six-membered cyclic phosphonates permits us to prepare esters of 3,7-dimethyl-2, 4-octadienoic acids with the predominance of the 2Z,4E isomer.