Dehydrogenation of lactones using benzeneseleninic anhydride. X-Ray crystal structure of 3β-acetoxy-14α-hydroxy-17a-oxa-D-homo-5α-androst-15-en-17-one

Abstract

δ-Lactones such as 4-oxa-5α-cholestan-3-one (1) and 3β-acetoxy-17a-oxa-D-homo-5α-androstan-17-one (3) undergo smooth dehydrogenation using benzeneseleninic anhydride in chlorobenzene at 100–130 °C. Reaction of compound (3) for longer periods of time additionally leads to the formation of C-14 hydroxylated derivatives. Similar reaction of a γ-lactone, 3-oxo-17βH-pregnane-21,17-carbolactone (7), afforded only ring A dehydrogenation and no dehydrogenation of the spiro-γ-lactone ring. The structure of compound (5) was confirmed by a single-crystal X-ray analysis.