US Patent 7951953 Conversion of 2-pyrazolines to pyrazoles using bromine

This invention relates to a method for preparing a compound of Formula 1 wherein L, R1, R2 and X are as defined in the disclosure, comprising contacting a 2 pyrazoline of Formula 2 with bromine at a temperature of at least about 80° C. (Formula 1) (Formula 2). This invention also discloses preparation of a compound of Formula 3 wherein X, Z, R5, R6, R7, R8a, R8b and n are as defined in the disclosure, using a compound of Formula 1a wherein R10 is as defined in the disclosure, prepared by the aforesaid method for preparing a compound of Formula 1. (Formula 3) (Formula 4).