Unsymmetrical azines via triisopropylsilylhydrazine

Triisopropylsilylhydrazine, (1), easily prepared from anhydrous hydrazine and chlorotriisopropylsilane (TIPSCl), readily converts aldehydes and ketones to their triisopropylsilyl hydrazones (2 (61-85%)). Desilylation of 2 with TBAF in the presence of a second aldehyde or ketone cleanly produces the desired unsymmetrical azines (3 (74–92%)).