"The chemical history of the pill begins with the isolation of progesterone in May 1933 by Corner and Allen. With the help of Dr. Hickman from the research laboratory of the Eastman Kodak Company, they used high-vacuum distillation of the oils extracted from corpora lutea to isolate the hormone in a crystalline form which they named progestin. Before the end of that year, Wintersteiner and Allen determined the structural formula of the hormone (C21 H30 O2). This admittedly was not difficult, since the structural formula of pregnanediol was known from previous work by Butenandt. As Allen later recalled, the correct structural formula of progesterone had originally been sketched on a napkin during a lunch with William Strain, long before the definitive structural proof was furnished! In the summer of 1934 the isolation of crystalline progesterone hormone was announced also by Butenandt and Westfall in Danzig, by Slotta et al. in Breslau, and in Switzerland by Hartman and Wettstein. A short time later Butenandt and Schmidt converted pregnandiol to progesterone, and Fernholz succeeded in synthesizing progesterone from stigmasterol."