Substituent Effects on the Denitrogenation Mechanism of 1-Pyrazoline Derivatives

Abstract

Denitrogenation of azoalkanes is known to be an efficient method not only to generate radicals, but also to synthesize strained molecules. For example, the denitrogenation of 1-pyrazolines produces cyclopropane derivaties in high yields. However, for the denitrogenation of 3-electron-withdrawing group-substituted 1-pyrazolines, the main product is not the intramlecular cyclization product but a rearrangement product. In the present study, the substituent effect that control the product distributions was investigated with a combined experimental and theoretical studies.