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Synfacts 2010(6): 0720-0720  
DOI: 10.1055/s-0029-1220001
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart ˙ New York

BINAPHANE-Catalyzed Asymmetric Formal [2+2] Cycloaddition

Contributor(s): Benjamin List, Kristina Zumbansen
M. Mondal, A. A. Ibrahim, K. A. Wheeler, N. J. Kerrigan
Oakland University, Rochester and Eastern Illinois University, Charleston, USA
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Publication History

Publication Date:
20 May 2010 (online)

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Significance

Kerrigan and co-workers report a [2+2] cycloaddition of aldehydes and ketenes ­catalyzed by BINAPHANE providing access to highly substituted β-lactones. A variety of arylketo-ketenes and a range of electron-poor as well as electron-rich aldehydes could be applied in the developed method forming the corresponding products in high enantio- and diastereoselectivity. Noteworthy is the activation of unactivated aliphatic aldehydes with a high level of asymmetric induction (er > 95:5). Two competing mechanistic pathways are suggested to proceed via a phosphonium alkoxide (mechanism A) or via a phosphonium enolate intermediate (mechanism B).