llyl-3-methoxy-14beta-estra-1,3,5(10)-trien-17-one is converted regios
electively into the 14beta-acetonyl 17-ketone or the 14beta-formylethy
l 17-ketone, which undergo intramolecular aldol condensation or reduct
ive cyclisation respectively, leading to 14beta,17beta-propano analogu
es of estradiol.