A PRACTICAL REAGENT FOR THE SYNTHESIS OF SUBSTITUTED HYDRAZINES

A practical, inexpensive triprotected hydrazine reagent, toxycarbonyl- 1-(4-methylphenylsulfonyl)-hydrazine, 1-Boc-1-Tos-2-Z-hydrazine (2), h as been prepared on a 100 mmol scale and examined with respect to appl ication in stepwise synthesis of unsymmetrically substituted hydrazine s. The use of three protective groups excludes undesired substitution on the nitrogens even under forcing conditions. The initial alkylation which can be accomplished quantitatively is followed by the removal o f the tosyl moiety. Due to the presence of a Boc group on the sulfonam ide nitrogen atom, the otherwise rather stable sulfonamide function ca n be cleanly and efficiently cleaved reductively by magnesium in dry m ethanol to provide a second alkylation site. Such intermediates have r ecently been converted to tetrasubstituted hydrazines. With sonication this reduction is generally complete within 30 minutes. The new reage nt exhibits increased stability to base in comparison with its predece ssor and is more suitable and economical for work on a larger scale.