Addition of Cl2C: to (-)-O-menthyl acrylate under sonication-phase-transfer catalysis. Efficient synthesis of (+)- and (-)-(2-chlorocyclopropyl)methanol.
[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.
Masuno
Makoto N
MN
Department of Chemistry, University of California, Davis, California 95616, USA.
Young
Douglas M
DM
Hoepker
Alexander C
AC
Skepper
Colin K
CK
Molinski
Tadeusz F
TF
D000179:Acrylates / Q000737:chemistry*; D002384:Catalysis; D003521:Cyclopropanes / Q000737:chemistry*; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry*; D000432:Methanol / Q000031:analogs & derivatives* / Q000737:chemistry*; D013010:Sonication; D013237:Stereoisomerism
D000179:Acrylates; D003521:Cyclopropanes; D006843:Hydrocarbons, Chlorinated; C004260:dichlorocarbene; D000432:Methanol