N-Methylmorpholine (0.028 ml.) and isobutyl chloroformate (0.038 ml.) were successively added to a stirred solution of 7α-(9-methylaminononyl)oestra-1,3,5(10)-trien-3,17β-diol (Example 28; 0.08 g.) in tetrahydrofuran (3 ml.) and the mixture was stirred at laboratory temperature for 150 minutes. Saturated aqueous sodium bicarbonate solution (2 ml.) was added and the mixture was extracted three times with methylene chloride (10 ml. each time). The combined extracts were washed with water (5 ml.), dried and evaporated to dryness and there was thus obtained as residual oil isobutyl N-[9-(3,17β-dihydroxyoestra-1,3,5(10)-trien-7α-yl)nonyl]-N-methylcarbamoate.
