Energy of Concert and Origins of Regioselectivity for 1,3-Dipolar Cycloadditions of Diazomethane

Abstract

Mechanisms and regioselectivities in 1,3-dipolar cycloadditions of diazomethane with alkenes have been investigated with density functional theory (DFT) and DLPNO-CCSD(T) computations. The concerted but asynchronous pathway is shown to be favored by at least 6 kcal/mol over the stepwise diradical pathway in all diazomethane-alkene cycloadditions. Frontier molecular orbital calculations indicate a dominant HOMOdipole -> LUMOdipolarophile interaction in diazomethane cycloadditions involving electron-deficient alkenes, whereas for electron-rich alkenes, both frontier interactions contribute significantly, and the regioselectivity is governed by frontier coefficients.

Publisher

American Chemical Society

Publication Date

5-7-2021

Publication Title

Journal of Organic Chemistry

Department

Chemistry and Biochemistry

Document Type

Article

DOI

10.1021/acs.joc.1c00743

Keywords

Diradical mechanism, Orientation, Reactivity, Diazoalkanes

Language

English

Format

text

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