Stereoselectivity of Methyl Aryldiazoacetate Cyclopropanations of 1,1-Diarylethylene. Asymmetric Synthesis of a Cyclopropyl Analogue of Tamoxifen

[formula: see text] Dirhodium tetrakis(S-(N-dodecylbenzenesulfonyl)prolinate) (Rh2(S-DOSP)4)-catalyzed decomposition of methyl phenyldiazoacetate in the presence of 1,1-diarylethylenes results in intermolecular cyclopropanation with high enantioselectivity (up to 99% ee) and moderate diastereoselectivity (up to 80% de). The reaction was applied to the asymmetric synthesis of a cyclopropyl analogue of tamoxifen.