New steroidal heterocycles: synthesis and structure of androst-4-eno[3,2-f]-(s-triazolo[4,3-b]pyridazine), androstano[17,16-f]-(s-triazolo[4,3-b]pyridazines), and 2-(1,2,4-triazol-4-ylaminomethylene)-3-(1,2,4-triazol-4-ylamino)-5α-androst-2-ene

Abstract

The reaction of 4-amino-1,2,4-triazole (1) with the 2-hydroxymethylene-3-oxo-Δ⁴-steroid (2) and three 16-hydroxymethylene- 17-oxo -steroids gave solely and in good yield androst-4-eno[3,2-f]-(s-triazolo[4,3-b]pyridazine)(3), the androstano[17,16-f]-(s-triazolo[4,3-b]pyridazines)(14) and (15), and 3-methoxyestra-1,3,5(10)trieno[17,16-f]-(s-triazolo[4,3-b]pyradazine)(16) respectively. However, the reaction of 4-amino-1;2,4-triazole (1) with 2-hydroxymethylene-3-oxo-steroids without a Δ⁴-double bond, under analogous conditions resulted in the formation of 2-(1,2,4-triazol-4-ylaminomethylene)-3-(1,2,4-triazol-4-ylamino)-steroids (7) and (9), also in high yield. The structures of these products were established by i.r., u.v., ¹H n.m.r., and ¹³C n.m.r. spectroscopy. Chemical evidence for the mechanism of these condensation reactions is discussed. Although conditions favourable for Dimroth Rearrangement were employed, no such transformations were encountered during the synthesis of the steroidal triazolopyridazines.