Asymmetric Synthesis of Cyclobutanone via Lewis Acid Catalyzed Tandem Cyclopropanation/Semi-Pinacol Rearrangement
Journal of the American Chemical Society | 10 Aug 2018
SY Shim, Y Choi and DH Ryu
Chiral Lewis acid catalyzed asymmetric formation of cyclobutanones from α-silyloxyacroleins and α-alkyl or α-aryl diazoesters has been developed. In the presence of a chiral oxazaoborolidinium ion catalyst, various α-silyloxycyclobutanones possessing a chiral β-quaternary center were synthesized in high yield (up to 91%) with excellent enantio- and diastereoselectivity (up to 98% ee and up to > 20 : 1 dr) through tandem cyclopropanation/semi-pinacol rearrangement. The synthetic potential of this method was illustrated by conversion of the product to various cyclic compounds such as γ-lactone, cyclobutanol, and cyclopentanone.
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