Sodium chlorodifluoroacetate, reaction

Sodium chlorodifluoroacetate, reaction with triphenylphosphine and a,a,a-trifluoroacetophenone, 48, 116... 

Reaction of the cisoid methoxymethylene ketone (36) with decomposing sodium chlorodifluoroacetate yields two epimeric adducts in 42 and 28 % yield, respectively, to which structure (37) has been assigned on the basis of NMR... 

Sodium azide, reaction with l butyl chloroacetate, 46, 47 reaction with diazomum salt from o amino-f> -ni trobiphcny L, 46, 86 Sodium chlorodifluoroacetate, 47, SO reaction with tnphenylphosphme and benzaldehyde, 47, SO Sodium ethoxide, 46, 2S reaction with diethyl succinate, 46,2S Sodium formate as reducing agent in preparation of palladium catalyst, 46, 90... 

Benzaldehyde, condensation, with N-phenylhydroxylamine, 46,127 with chloroform, 48, 27 reaction with triphenylphosphine and sodium chlorodifluoroacetate, 47, 50... 

Aldehydes are converted into 1,1-difluoroethylenes by heating with triphenylphosphine and sodium chlorodifluoroacetate in glyme or diglyme. Under the same conditions, ketones do not react. However, Fuqua et ul. found that, if 1-methyl-2-pyrrolidone is used as solvent and tributylphosphine is used as base, satisfactory yields are obtained in reactions of ketones. 

S. A. Fuqua, W. G. Duncan, and R. M. Silverstein, Org. Syn., 47,49 (1967) definitive paper F. E. Elerkes and D. J. Burton, J. Org., 32, 1311 (1967). In the early work it was assumed that the reaction of sodium chlorodifluoroacetate in the presence of triphenyl-phosphinc involved formation of difluorocarbene, which then reacts with triphenylphosphine to form difluoromethylenetriphenylphosphorane, (C2H,i.,P—CF,. However, addition of tetra-methylethylene to the reaction in the presence of a ketone failed to yield any cyclopropane derivative. Herkes and Burton (loc. cit.) suggest that a phosphobetaine salt (a) is the intermediate which loses carbon dioxide to form the active reagent (b). 

Generation of difluorocarbene. In an early study1 of the reaction of difluoro-carbene with steroidal double bonds, the methylenation was conducted by portion wise addition of an excess of dry sodium chlorodifluoroacetate to a diglyme solution of the substrate at temperatures of 120-150°. The same laboratory (Syntex)2 now reports that the reaction is improved by addition of a solution of the salt in diglyme to a refluxing diglyme solution of the substrate. The reaction with A4-6- and AI 4 a-3-ketosteroids results mainly in addition to the Afi-double bond to give 6a,7a-difluoromethylene-A4- and A -4-3-ketones, respectively. 

In an informal publication, Venier has reported the reaction of several sulphines with carbene precursors, generally to produce olefins or the products of further reaction of the olefins with the carbenoid agents. Thus, 9>fluorenylidenesulphine with sodium trichloroacetate afforded dichloro benzofulvene, a reaction exactly analogous to that undergone by 9-dimethylsulphoniumfluorenylide. The same sulphine with sodium chlorodifluoroacetate gave the tetrafluoro-spiro-compound (94), whereas... 

The reaction of difluorocarbene, generated by thermal decomposition of sodium chlorodifluoroacetate, with 2-benzylidene-5a-cholestan-3-one 57 and related substrates afforded 3-fluoro-2-phenylfuran fused to steroid fragment via C4-C5 bond 58. 2-Benzylidenecyclohexanone reacted similarly with difluorocarbene yielding 3-fluoro-2-phenyl-4,5,6,7-tetrahydrobenzofuran in low yield [42]. 

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