Synthesis and characterization of () and ()-1,2-difluoroethenediylbisphosphonates

Solid‐State Structure of a Bromo(difluoromethylenephosphonato)cuprate – a Key Intermediate for the Synthesis of α,α‐Difluoromethylenephosphonates

“…In accordance with the suggestion of Burton and Yokomatsu,, [7e] the addition of one equivalent of CuBr to a DMF solution of BrZnCF 2 P(O)(O i Pr) 2 gives rise to the formation of the heteroorganocuprate [Zn{Cu(Br){CF 2 P(O)(O i Pr) 2 }} 2 (dmf) 4 ] [Equation (4)], which was isolated from a cold THF solution as colorless needles. The light‐ and air‐sensitive cuprate can be stored under a N 2 atmosphere at –28 °C in the dark for weeks.…”

“…Whereas the organocopper compound is insoluble in ethereal solvents, its solutions in CH 3 CN, DMF, and DMSO suffer from decomposition to E/Z ( i PrO) 2 (O)PCF=CFP(O)( i PrO) 2 and HCF 2 P(O)(O i Pr) 2 , as was previously reported by Burton. [9a] In our studies, the formation of ( i PrO) 2 (O)PCF 2 CF 2 P(O)( i PrO) 2 , as caused by a radical decomposition mechanism, was not observed. [7e] The analysis of the 19 F NMR spectra of the DMSO solution shows only traces of decomposition products after 25 days of storage.…”

“…The good agreement of the data with the model of a first‐order decay implies a rate‐determining step of the decay proceeding over one distinct pathway, presumably a carbenoid‐like structure. [7c], [9a]…”

“…Despite the number of reports on copper mediated couplings with BrZnCF 2 P(O)(OR) 2 , the constitution and molecular structure of the copper reagent remained virtually obscure. Yokomatsu and Burton, [7e] postulated a mixed Cu/Zn species as the reactive intermediate (Scheme ).…”

The Synthesis of Dialkyl α-Halogenated Methylphosphonates

“…127,128 This method is now widely used. 96,[129][130][131][132] The initial reaction involved a 24 hours reflux, but this was recently shortened to one and an half hours with a slight modification in the conditions (refluxing solvent). 99 Other dialkyl bromodifluoromethylphosphonates were obtained in the same way (dimethyl, 55 % 127 ; diisopropyl, 42 % 127 ; dibutyl, 65 % 127 to quantitative yield 95,121 ).…”