Novel and facile generation of azomethine imines from α-silylnitrosamines and subsequent cycloaddition with dipolarophiles leading to a variety of pyrazole derivatives have been developed. The key to the reaction is a 1, 4-silatropic shift caused by strong affinity of the nitroso oxygen atom toward the silicon atom. Thus, α-silylnitrosamines are treated with 1 equiv. of dipolarophiles in refluxing toluene for 1 h to give pyrazole derivatives in good to ...