D-Homo-4-androstene-3,17a-dione

Subsequently the trisanellation reagent, 7-acetoxy-l,ll-dodecadien-3-one 0M>) was prepared from the bisanellation reagent (67), and the synthesis of D-homo-19-norandrosta-4-en-3-one (82) was carried out from (79) as shown below. For the A-ring formation, the unmasking of the termi double bond and hydrogenation afforded the 1,5-diketone (81), which was subjected to intramolecular aldol condensation to give D-homo-4-androstene-3,17a-dione (82 Scheme 23). 

Analogous ring enlargement reactions, including a radical promoted Q incorporation, are known in steroid chemistry Irradiation of the 11/3-nitrite of 4-androstene-ll/3-ol-3,17-dione (VII/59) (Barton reaction) in toluene gave 18-nor-D-homo-4,13(17a)-androstadiene-llj8-ol-3,17-dione (VII/63) [33]. For Q radical rearrangements mediated by cobalamin, see [34] [35] [36] [37]. 

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