Syntheses of 2,3-dioxoalkylphosphonates and other novel β-ketophosphonates as well as of a phosphinopyruvamide (= (alkyloxyphosphinyl)pyruvamide)

Article abstract of DOI:10.1002/hlca.19960790329

The new 3-(diethoxyphosphoryl)-2-oxopropanoates 5 and 6 and -propanamides 1-4 with various amino substituents at C(3) were prepared (Scheme 2). These compounds exist, depending on N-substitution, as pure (E)-enols (in the case of 1 and 5) or as a mixture of three tautomeric forms (in the case of 1-4 and 6). The configuration could be unambiguously assigned from the ¹H-, ¹³C-, and ³¹P-NMR spectra. Phosphinopyruvamide ( = (alkyloxyphosphinyl)pyruvamide) 9 was prepared in a similar manner in spite of the instability of phosphinate-derived carbanions. Some 3-(ethoxyimino)-2-oxobutylphosphonates, 11-13 (Scheme 5), and various 3,3-dimethoxy-2-oxoalkylphosphonates, 19-23 and 26-33 (Scheme 6), were available from the reaction of lithioalkylphosphonates with 2-(ethoxyimino)propanoates and 2,2-dimethoxyalkanoates, respectively. The 3,3-dimethoxybutylphosphonates 20, and 26-30 were cleaved to give 2,3-dioxobutylphosphonates 34-39 (Scheme 6). This method provides easy access to a new class of potentially pharmaceutically useful compounds.