Catalytic asymmetric cyclopropanation of allylic alcohols with titanium-TADDOLate: scope of the cyclopropanation reaction.
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.
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Département de Chimie, Université de Montréal, P.O. 6128, Station Downtown, Montréal, Québec, Canada H3C 3J7.
Molinaro
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Brochu
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