Phosphonium, triphenyl-, bromide, ethyl ester

Phosphonium, (carboxymelhyl)triphenyl-, bromide, ethyl ester, 70, 246 Phosphonous dichloride, phenyl- (644-97-3), 70, 273 Phthalimide, N-(3-bromopropyl)-, 70. 195 Piperidine, 2-methyl- (109-05-7), 70, 265 Pirkle Type 1-A column, 70, 64... 

Ethyl 4,4,4-trifluoro-2-(triphenylphosphoranylidene)acetoacetate Butanoic acid, 4,4,4-trifluoro-3-oxo-2-(triphenylphosphoranylidene)-, ethyl ester (11) (83961-56-2) (Carbethoxymethyl)triphenylphosphonium bromide Phosphonium, (carboxymethyt)triphenyl-, bromide, ethyl ester (8) Phosphonium, (2-ethoxy-2-oxoethyl)triphenyl-, bromide (9) (1530-45-6)... 

There is no general solvent that is useful for all reactions, and BTF naturally has its limitations. In addition to the limitations posed by the freezing point, boiling point and chemical stability mentioned before, BTF is not very Lewis-basic and therefore is not a good substitute for reactions that require solvents like ethers, DMF, DMSO, etc. Not surprisingly, ions are not readily dissolved in BTF and many types of anionic reactions do not work well in BTF. For example, attempted deprotonations of esters and ketones with LDA in BTF were not successful. Reaction of diethyl malonate with NaH (5 equiv) and reaction with Mel[72] (6 equiv) in BTF was very heterogeneous and yielded 60% of the di-methylated product, compared to 89% in THF. No reaction was observed if the same malonate anion was used as a nucleophile in a Pd-catalyzed allylic substitution reaction in BTF (see 3.7). Wittig reactions also did not work very well in BTF. The ylid of ethyl triphenyl phosphonium bromide [73] was formed only slowly in BTF, and the characteristic deep red color was never obtained. 

NaH stirred ca. 45 min. at 65-70° under Ng in excess dimethyl sulfoxide until Hg-evolution is complete, allowed to react with 1 equivalent of ethyl triphenyl-phosphonium bromide, then with 0.85 equivalent of benzophenone 1,1-di-phenyl-l-propene. Y 97.5%.—The reactivity of the methylsulfinyl carbanion (formed by reaction of NaH with dimethyl sulfoxide), which is even more basic than the trityl anion, is sufficient to convert phosphonium salts into ylides thereby permitting a simple and convenient modification of the Wittig reaction. E. J. Gorey and M. Ghaykowsky, Am. Soc. 8A, 866 (1962) / -diketones from carboxylic acid esters and ketones (s. Synth. Meth. 6, 737), sym. ) -diketones, s. J. J. Bloomfield, J. Org. Chem. 27, 2742 (1962). 

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