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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.

The cyclopropanation of (−)-8-phenylmenthyl (E)-3-aryl-2-phosphonoacrylates E-3a–d with dimethyloxosulfonium methylide and diazomethane affords the corresponding trans cyclopropane derivatives as the major diastereomers with high diastereoselectivity. On the other hand, the cyclopropanation of (−)-8-phenylmenthyl (Z)-3-aryl-2-phosphonoacrylates Z-3a–d and (−)-menthyl derivative 4 gives mixtures of cis and trans cyclopropane derivatives with low diastereoselectivity. The high diastereoselectivity in the cyclopropanation of (E)-acrylates E-3a–d can be rationalized by considering the π–π interaction between the phenyl ring of the chiral auxiliary and the acrylate moiety in the s-cis conformer. The low selectivity in the cyclopropanation of (Z)-acrylates (Z-3a–d and 4) can be attributed to a low-lying conformer with the acrylate moiety twisted out of conjugation.

The first stereoselective total synthesis of a potent antitumor alkaloid, discorhabdin A (1), which is a unique sulfur-containing pyrroloiminoquinone alkaloid, is described. The key step in the stereocontrolled total synthesis of 1 involves both a diastereoselective oxidative spirocyclization using a hypervalent iodine(III) reagent and an efficient construction of the labile and highly strained N,S-acetal skeleton. These methodologies provide a breakthrough in the total syntheses of these promising new antitumor agents, discorhabdins and their analogues, which should serve as valuable probes for structure-activity studies.