title: Brønsted Acid/Lewis Acid Cooperatively Catalyzed Addition of Diazoester to 2H-chromene Acetals.
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.
authors.affiliation: School of Materials Science and Engineering University of Science and Technology Beijing 30 Xueyuan Road, Haidian district, Beijing, 100083 (P. R. China).
authors.forename: Yi
authors.initials: Y
authors.lastname: Luan
authors.affiliation: Chemistry Department Boston University 24 Cummington st. Boston, Massachusetts, 02215 (U.S.).
authors.forename: Yue
authors.initials: Y
authors.lastname: Qi
authors.affiliation: School of Materials Science and Engineering University of Science and Technology Beijing 30 Xueyuan Road, Haidian district, Beijing, 100083 (P. R. China).
authors.forename: Hongyi
authors.initials: H
authors.lastname: Gao
authors.affiliation: School of Materials Science and Engineering University of Science and Technology Beijing 30 Xueyuan Road, Haidian district, Beijing, 100083 (P. R. China).
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Ma
authors.affiliation: Chemistry Department Boston University 24 Cummington st. Boston, Massachusetts, 02215 (U.S.).
authors.forename: Scott E
authors.initials: SE
authors.lastname: Schaus
keywords: Brønsted Acid; Diazo compounds; Enantioselectivity; Lewis acid; Oxocarbenium