Addition of Cl2C: to (-)-O-menthyl acrylate under sonication-phase-transfer catalysis. Efficient synthesis of (+)- and (-)-(2-chlorocyclopropyl)methanol |
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Authors: | Masuno Makoto N Young Douglas M Hoepker Alexander C Skepper Colin K Molinski Tadeusz F |
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Institution: | Department of Chemistry, University of California, Davis, California 95616, USA. |
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Abstract: | reaction: see text] Dichlorocyclopropanation of (-)-O-menthyl acrylate under conditions of phase-transfer catalysis (CHCl3, KOH, tetramethylammonium bromide), with sonication, gives excellent yields (85-94%) of the corresponding dichlorocyclopropanecarboxylate ester compared to thermal conditions (90 degrees C, 56%). No diastereoselectivity was observed, but one isomer was isolated pure by fractional crystallization. The measured kinetic isotope effect (initial rate (CHCl3)/rate (CDCl3) approximately 1.7) suggests deprotonation of CHCl3 as the rate-limiting step. |
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