Crystal and molecular structures of (20R)-20-aminopregn-5-en-3 beta-ol and(20S)-20-aminopregn-5-en-3 beta-ol hydrochloride

Two epimers of 20-aminopregn-5-en-3 beta -ol differing in configuration at C(20) have been synthesized and their structures have been determined by si ngle crystal X-ray diffraction methods. The (20R)-epimer (1) crystallized i n the orthorhombic system, space group P2(1)2(1)2(1), with a = 9.0432(5) An gstrom, b = 13.3446(7) Angstrom, c = 15.1086(8) Angstrom, and Z = 4. The (2 0S)-epimer hydrochloride hydrate (2 hydrate) crystallized in the monoclinic system, space group C2, with a = 31.0501(3) Angstrom, b = 11.8221(1) Angst rom, c = 11.9703(2) Angstrom, beta= 98.5140(10)degrees, and Z = 8. The abso lute configurations at the C(20) chiral centers for the title compounds wer e unequivocally established for the first time. The asymmetric unit cell of 2 hydrate contained two steroid molecules, A and B, two hydrochloride mole cules, and two molecules of water. The crystal packing for both diastereome rs was strongly influenced by the presence of intermolecular hydrogen bondi ng. The molecules of 1 were linked in a head-to-tail fashion via hydrogen b onds between the hydroxyl group of the ring A and the amino group of the si de chain of the ring D. The two molecules A and B of 2 hydrate were held to gether in head-to-head and head-to-tail fashions by a three-dimensional net work of hydrogen bonds involving chlorine ions. disordered water molecules, and hydroxyl-amino groups interactions.