Crystal structure of ent-(7β,11α)-dihydroxy-1-oxo-kaur-16-en-19-oic acid, C20H28O5

Abstract

C20H28O5, orthorhombic, P2\2\2 (No. 19), a = 7.8782(1) Â, b= 14.2772(2) Â,c= 15.7818(2) Â, V= 1775.1 A ,Z = 4, Rt mp 520 Κ 521 K, [a]° = -88 (c = 0.105, MeOH). Discussion The ring A/B is in a rrans-conformation. The rings A, Β and C adopt a distorted c/mir-conformation. The ring D presents an envelope conformation. An intramolecular hydrogen bond between the 05 and 04 atoms with </(05 H40) = 1.83(2) Â, makes the carbonyl bond distance of CI—05 (1.222(1) Â) longer than that of C19—02 (1.207(2) A) which is not involved in any hydrogen bonding. The most common conformation of an intermolecular hydrogen bonding in the carboxylic group in the kaurane compounds is a cyclic hydrogen-bonded dimer [1]. However, in the case of the title compound, the molecules are mainly linked by the network intermolecular hydrogen bonds between the hydrogen atom of the carboxylic group and 01 hydroxyl atom and forms infinite chains. The H30—01 distance is 1.77(2) Â and the angle ?03-H30 Ol is 161.7°; symmetry operation of Ol is x-l, y, z. The hydroxyl Ol and 04 atoms also act both as a donor and an acceptor in hydrogen bonding. The H10—04 distance is 2.005(2) Â and the angle ? 0 1 H 1 0 0 4 is 160.8°. Table 1. Data collection and handling.