The cyclopropanation of (−)-8-phenylmenthyl (E)-3-aryl-2-phosphonoacrylates with dimethyloxosulfonium methylide and diazomethane afforded the corresponding trans cyclopropane derivatives with high diastereoselectivity as the major diastereomer. The high selectivity is understandable in terms of the π–π interaction between the phenyl ring of the chiral auxiliary and the acrylate moiety.