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. 2014 Nov 1;2014(31):6868-6872.
doi: 10.1002/ejoc.201403043.

Brønsted Acid/Lewis Acid Cooperatively Catalyzed Addition of Diazoester to 2 H-chromene Acetals

Yi Luan  1 , Yue Qi  2 , Hongyi Gao  1 , Qianqian Ma  1 , Scott E Schaus  2
Affiliations

Brønsted Acid/Lewis Acid Cooperatively Catalyzed Addition of Diazoester to 2 H-chromene Acetals

Yi Luan et al. European J Org Chem. .

Abstract

A novel Brønsted acid/Lewis acid dual catalyst system has been developed to promote an efficient C-C bond formation between a range of oxocarbenium precursors derived from chromene acetals and ethyl diazoacetate. The reaction proceeds under mild conditions and is tolerant of common functionalized 2H-chromene and isochromene acetals. In addition, an asymmetric variant of diazoacetate addition towards 2H-chromene acetal is described. Continued investigations include the further optimization of asymmetric induction towards the formation of diazo ester substituted 2H-chromene.

Keywords: Brønsted Acid; Diazo compounds; Enantioselectivity; Lewis acid; Oxocarbenium.

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Figures

Figure 1
Figure 1
Nucleophilic addition to isochromene acetal 8.
Scheme 1
Scheme 1
2H-chromene acetal addition reaction.
See this image and copyright information in PMC

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