13,14-Didehy dro- 1 l-deoxy- 15-ketoprostaglandin E 1 (at 17 3 K), C20H30 O4

M r= 334.5, monoclinic, P2Jn, a= 5.544 (1), b = 12-834 (2), c= 27.587 (6)/k, fl= 92.22 (2) °, V= 1961.4 ./t 3, Z = 4, D x = 1.13 g cm -3, Mo Ko., 2 = 0.71069/k, /1= 0.72 cm -~, F(000) = 728, final R =0.061 for 2463 unique reflections above background (I > 2cr(/)l. The molecule does not have the hairpin conformation that is characteristic of most prostaglandin molecules. Instead, an 'L'-shaped confor- mation is revealed that is similar to the structure of prostaglandin B~. The alkyl chains have the fully extended all-trans conformation. The five-atom ring has an envelope conformation. The stereochemical features of the title compound are compared with those of prostaglandin E l and two other prostaglandin E l analogs.