Structure Determination of Natural Epoxycyclopentanes by X - ray Crystallography and NMR Spectroscopy '

of the phosphorus-oxygen bond renders reduction irreversible. Because trialkylphosphines are kinetically stable in aqueous solution, selective for the reduction of the disulfide linkage, and unreactive toward many other functional groups, they are attractive as reducing agents in biochemical systems. Their utility has been limited by the low solubility of most simple trialkylphosphines in water, and their acceptability as reagents (especially in biochemistry) by the odor and ease of autoxidation of many species with low molecular weights. Water-soluble phosphines have been used as reducing agents, as chelating agenta, and as ligands. Sulfonylated triphenylphosphines have been used extensively as ligands for water-soluble metal catalysts.2 They are the subject of several ~ a t e n t s . ~ A commercially available water-soluble triarylphosphine, tris(4-carboxyphenyl)phosphine, is relatively expen~ive.~ Other water-soluble phosphines have been made.S*6 Tris(hydroxymethyl)phosphine, a liquid with an unpleasant odor, can generate formaldehyde and other byproducts derived from it in reductions of proteins.’ These characteristics have prevented the general use of phosphines as reducing agents for water-soluble disulfides. Here we describe a convenient preparation of tris(2carboxyethy1)phosphine hydrochloride (TCEP.HC1,l.HCl) by acidic hydrolysis of the commercially available tris(2cyanoethy1)phosphine (2) (eq 2) and demonstrate the