A-Homo-24-nor-4-oxachola-14,20,22-trien-3-one,1,12-bis(acetyloxy)-21,23-epoxy-4a,4a,8-trimethyl-7-[(2-methyl-1-oxo-2-butenyl)oxy]-,[1a,5a,7a(E),12a,13a,17a]-