2-Alkoxy-3-hydroxy-1,2-oxaphospholane-2-oxides (α-hydroxyphostones)

• Published in: Zeitschrift für Naturforschung. B, A journal of chemical sciences Vol. 38; no. 9; pp. 1122 - 1129
• Main Authors: Pilgram, Kurt H., Gale, Laird H., Pollard, Glenn E.
• Format: Journal Article
• Language: English
• Published: Verlag der Zeitschrift für Naturforschung 01.09.1983
• Subjects: Dimerization; Hydrogen Bonding; Stereochemistry; X-Ray
• ISSN: 0932-0776; 1865-7117
• DOI: 10.1515/znb-1983-0914

The addition-cyclocondensation reactions of three β-hydroxyketones with four dialkyl phosphites gave 2-alkoxy-3-hydroxy-1,2-oxaphospholane-2-oxides (“α-hydroxyphostones”) (7), in moderate yields. In the solid state and in solution, these compounds exist as dimers with hydrogen bonding between the hydroxyl group and the phosphoryl oxygen atom of an adjacent molecule. The crystal and molecular structure of 3-hydroxy-2-methoxy-3,5,5-trimethyl-1,2-oxaphospholane-2-oxide (7 a) has been determined by single-crystal X-ray crystallography: C P, monoclinic space group P2-1/n, cell dimensions a = 8.087(1) Å, b = 13.386(2) Å, c = 9.306(1) Å, V = 1007.4 Å , Z = 4, final R = 0.052. The five-membered ring is puckered, with the carbon bearing the OH and CH groups lying out of the plane of the remaining four atoms in the ring. The doubly bonded oxygen attached to the phosphorus atom and the hydroxyl oxygen are in a cis-relationship. The O(1)-O(4) intermolecular bond distance of 2.75 Å suggests hydrogen bonding. The O(1)-H(1) intermolecular bond distance of 1.97 Å is consistent with this conclusion.