Remarkable tolerance of ethynyl steroids to air and water in microwave-assisted hydrophosphinylation: Reaction scope and limitations Robert A. Stockland Jr. a, * , Adam J. Lipman a , John A. Bawiec III a , Peter E. Morrison a , Ilia A. Guzei b , Peter M. Findeis a , John F. Tamblin a a Department of Chemistry, Bucknell University, 312 Rooke Chemistry, Lewisburg, PA 17837, United States b Molecular Structure Laboratory, Department of Chemistry, University of Wisconsin, Madison, WI 53706, United States Received 18 April 2006; received in revised form 3 June 2006; accepted 3 June 2006 Available online 15 June 2006 Abstract The microwave-assisted hydrophosphinylation of propargyl alcohols has been investigated using group 9 catalysts under solvent-free conditions as well as with pure water, ethyl lactate, or THF as the solvent. Reactions involving simple propargyl alcohols gave mixtures containing significant amounts of elimination products. In contrast, analogous reactions involving ethynyl steroids afforded a single spe- cies with only trace amounts of elimination products. The molecular structures of several derivatives have been determined and are discussed. Ó 2006 Elsevier B.V. All rights reserved. Keywords: Hydrophosphinylation; Rhodium; Microwave-assisted; Aqueous 1. Introduction The development of organometallic reactions that pro- ceed in water as well as other ‘‘green’’ solvents is a current and challenging goal [1,2]. Recent developments include the synthesis of small molecules and polymeric materials through Suzuki-type coupling reactions [3,4], the aqueous phase reduction of ketones and aldehydes [5], and the use of a sulfonated XANTPHOS ligand for a regioselective hydroformylation reaction in water [6]. Additionally, water is an attractive solvent for microwave-assisted chemistry due to its high absorption of microwave radiation. The transition metal catalyzed addition of P(O)–H bonds to alkenes and alkynes is a powerful way to generate P–C bonds [7–11]. Despite the intense amount of research that has been devoted to this chemistry, a number of chal- lenges still remain. For example, propargyl alcohols are a particularly problematic class of compounds for metal catalyzed hydrophosphinylation reactions due to the gener- ation of a wide range of products. This product distribu- tion often depends upon the metal catalyst and additives (Fig. 1). Recently, Uemura et al. found that dinuclear ruthenium catalysts promoted the conversion of propargyl alcohols to ethynyl phosphine oxides in 1,2-dichloroethane [12]. Han et al. recently reported that a nickel catalyst gen- erated mixtures of phosphinoyl 1,3-butadienes and alkenyl phosphine oxides in THF [13]. Tanaka et al. has shown that Wilkinson’s catalyst promoted the addition of a pina- col derived hydrogen phosphonate to 2-methyl-3-butyn-2- ol in THF [14]. Ethynyl steroids are a particularly attractive class of propargyl alcohols. The development of methodology for the functionalization of ethynyl steroids is an important 0022-328X/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jorganchem.2006.06.007 * Corresponding author. Tel.: +1 570 577 1665; fax: +1 570 577 1739. E-mail address: rstockla@bucknell.edu (R.A. Stockland Jr.). www.elsevier.com/locate/jorganchem Journal of Organometallic Chemistry 691 (2006) 4042–4053