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Catalytic Asymmetric Cyclopropanation of Allylic Alcohols with Titanium-TADDOLate:  Scope of the Cyclopropanation Reaction

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journal contribution
posted on 07.11.2001, 00:00 by André B. Charette, Carmela Molinaro, Christian Brochu
A substoichiometric amount of titanium-TADDOLate complex was effective at catalyzing the cyclopropanation reaction of allylic alcohols in the presence 1 equiv of bis(iodomethyl)zinc. After initial optimization of the catalyst structure, excellent yields and enantiomeric ratios were obtained for 3-aryl- or 3-heteroaryl-substituted allylic alcohols (up to 97:3). Alkyl-substituted allylic alcohols gave modest yields and enantiomeric ratios (up to 87:13) but these compare favorably with those observed with other substoichiometric chiral ligands. The full synthetic scope of the reaction is presented in this paper.