Part I. 3α-Hydroxy-5,6α-epoxy-cholestane (1d)¹ and 3β-hydroxy-5,6β-epoxy-cholestane (2b) have been reacted with BF₃-etherate in benzene. The 3α-hydroxy-(2c) and the 3α-acetoxy-(2e) 5,6β-epoxy-cholestanes¹ have been prepared and their reactions on treatment with BF₃-etherate examined. Part II. 3β,6β-diacetoxy-5α-hydroxy-9β-cholestane (73a) and 3β,5α,6β-triacetoxy-9β-cholestane (74) have been prepared, and reacted with H₂SO₄-Ac₂O-AcOH² and BF₃-etherate-Ac₂O respectively. The hydroxyl-diacetate (73a) has also been reacted with SOCl₂-pyridine. The 3β-hydroxy- (81b) 5,6α-epoxy-9β-cholestanes have been prepared, and reacted with BF₃-etherate in benzene and/or ether. The major products have been shown to be ring A spiran compounds with some being formed via a ring B fragmentation reaction.