Synthesis of phosphinic acids on the basis of hypophosphites: VI. General methods for synthesis of pseudo-γ-glutamylpeptides

A general method for synthesis of 2-substituted pseudo-γ-glutamylpeptides, namely, 2-(hydroxycarbonyl)ethyl]3-amino-3-(hydroxycarbonyl)propyl]phosphinic acids I which are phosphinic acid analogs of γ-glutamylpeptides. Bis(trimethylsilyl) hypophosphite (IV) formed from ammonium hypophosphite (II) in situ was added to the respective α-substituted acrylate to form bis(trimethylsilyl) 2-R-2-(alkoxycarbonyl)ethyl]-phosphonites V. Treatment of compounds V in situ with excess dibromoethane followed by alcoholysis gave 2-R-2-(alkoxycarbonyl)ethyl](2-bromoethyl)phosphinic acids VI which without isolation were treated with excess triethyl orthoformate. The simultanious esterification and dehydrobromination led to 2-R-2-(alkoxy-carbonyl)ethyl](vinyl)phosphinates III which were isolated and characterized. The Michael addition of diethyl acetamidomalonate to vinylphosphinates III followed by acid hydrolysis of phosphinates VII without their isolation resulted in formation of target 2-R-2-(hydroxycarbonyl)ethyl]3-amino-3-(hydroxycarbonyl)]proly]phosphinic acids-pseudo-γ-glutamylpeptides I. Original Russian Text V.V. Ragulin, 2007, published in Zhurnal Obshchei Khimii, 2007, Vol. 77, No. 5, pp. 763–768. For communication V, see 1].