Organometallic complexes containing 17-ethynyl-179-hydroxyandrost-4-en-3- one and related ethynyl steroids

Abstract

Gold complexes of 17-ethynyl-17β-hydroxyandrost-4-en-3-one, 17-ethynyl-3-methoxyestra-1,3,5(10)-trien-17β-ol, and 17α- ethynylestra-1,3,5(10)-triene-3,17β-diol have been prepared and characterized. The title compounds were prepared by treatment of the parent ethynyl steroid with sodium bis(trimethylsilyl)amide followed by the addition of R 3PAuCl. Using a variety of phosphorus donors, a total of 36 gold steroid compounds were readily prepared using this approach. Compounds containing basic low cone angle phosphines such as PMe 3 and PEt 3 exhibited broad signals in the 13C{ 1H} NMR spectrum for the alkyne moiety, while compounds containing triarylphosphines or moderately bulky trialkylphosphines exhibited sharp signals. Correlations between common measures of phosphine donor ability with 2J CP and 3J CP as well as changes in the 31P chemical shift were made. While the use of low cone angle phosphines was successful, analogous reactions with trimesitylphosphine or tris (2,4,6-trimethoxyphenyl)phosphine resulted in intractable mixtures containing significant amounts of free phosphine. The incorporation of electron-withdrawing groups into the organic fragment of the phosphine donors was tolerated except for P(C 6F 5) 3, where displacement of the phosphine was observed. The molecular structures of five representative examples are presented and discussed. These determinations represent the first structurally characterized examples where the transition metal is σ-bound to the ethynyl fragment of the steroid. © 2006 American Chemical Society.