Trifluromethyl substitution on the pyrazole ring was found to enhance photoreactivity via the P4 pathway which involves interchange of the N2‐C3 ring atoms. Thus, 1‐methyl‐3‐(trifluromethyl)pyrazole (1) and 1‐methyl‐5‐(trifluromethyl)pyrazole (3) transposed with a P4/P6 or P4/P6+P7 ratio of 2.1:1. 1‐methyl‐4‐(trifluromethyl)pyrazole (2) transposed regiospecifically by the P4 transposition pathway. Compounds 2 and 3 were also observed to undergo photocleavage to yield enaminonitrile and enaminoisocyanide products.

Trifluoromethyl substitution on the pyrazole ring was found to enhance photoreactivity via the P 4 pathway which involves interchange of the N2-C3 ring atoms. Thus, 1-methyl-3-(trifluoromethyl)pyrazole (1) and 1-methyl-5-(trifluoromethyl)pyrazole (3) transposed with a P 4 /P 6 or P 4 /P 6 +P 7 ratio of 2.1:1. 1-Methyl-4-(trifluoromethyl)pyrazole (2) transposed regiospecifically by the P 4 transposition pathway. Compounds 2 and 3 were also observed to undergo photocleavage to yield enaminonitrile and enaminoisocyanide products.