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. Author manuscript; available in PMC: 2012 Jan 1.
Published in final edited form as: Steroids. 2010 Nov 9;76(1-2):193–203. doi: 10.1016/j.steroids.2010.10.009

Scheme 1.

Scheme 1

Synthesis of 3β,21-dihydroxypregna-5,7-dien-20-one (4) and its UVB-driven photolysis to vitamin D, tachysterol and lumisterol analogues. Reagents and conditions: (a) Ac2O, microwave, p-toluenesulfonic acid monohydrate; (b) Dibromantin, 2,2′-azobisisobutyronitrile, benzene/hexane (1:1), 100°C, reflux; (c) Bu4NBr, Bu4NF, THF, room temperature; (d) K2CO3, MeOH-THF, H2O, argon, room temperature.