An unprecedented rearrangement of a 1,1-diprotected hydrazine derivative. Structure revision of a catalyst-containing by-product

Treatment of 1-Boc-1-tosyl-hydrazine with 1,1,3,3-tetramethylguanidine (TMG) gave rise to two products, one containing and the other not containing TMG. The latter was identified as 1-Boc-2-tosyl-hydrazine. This rearrangement provided useful insight into the nature of the first product that had previously been isolated and assigned an incorrect tentative structure. To rationalize the results a plausible mechanism via a common intermediate, involving TMG as a nucleophilic catalyst is proposed. A simpler procedure for the preparation of the starting material is also presented.