Ethyl bromofluoroacetate

Replacement of bromine in ethyl bromofluoroacetate by thiolate anions occurs easily [44] (equation 40)... 

Alkyl diethylphosphononuoroacetates have been used extensively in ol fi-nanon procedures [69], principally forming the ffJ-a-fluoro-a.P-unsaturated esters with very high stereoselectivity [70] (equation 61) (Table 22). Preparation of the ethyl diethylphosphonofluoroacetate from ethyl fluoroacetate has obviated the necessity to prepare ethyl bromofluoroacetate from bromine fluoride and ethyl diazoacetate [71],... 

The enolates of fluoroacetate or fluorothioacetate esters are generated either through deprotonation with a lithium amide or by an in situ reduction of ethyl bromofluoroacetate with zinc. These enolates can undergo diverse reactions with electrophiles (Figure 2.7) ... 

Ethyl fluorophosphonate is commercially available it is prepared through a Michael-Arbuzov reaction between triethyl phosphite and ethyl bromofluoroacetate. 

Ethyl Bromofluoroacetate from Ethyl Diazoacetate Typical Procedure 31... 

The reaction of a-fluoro-/f-hydroxy-a-phenylsulfanyl esters 4, which can be readily synthesized from aldehydes and ethyl bromofluoroacetate, with diethylaminosulfur triduoride leads to the formation of a,o -difluoro-/I-phenylsulfanyl esters Instead of the expected substitution of the j8-hydroxy group by fluorine, a rearrangement via an episulfonium ion and addition of a fluoride ion % to the ester function gives the a,a-difluorinated product 5. The reaction proceeds under mild conditions with moderate to good yields. In the case of ethyl 2-fluoro-3-hydroxy-3-phenyl-2-(phcnylsulfanyl)propanoate only the nonrearranged product ethyl 2.3-di-fluoro-3-phenyl-2-(phenylsulfanyr)propanoate was isolated. 

Ethyl Bromofluoroacetate (Table 9, Entry 14) Typical Procedure " - ... 

Bromo(ethoxycarbonyl)fluoromethyl]phenylmercury A 500-mL, three-neck flask equipped with an addition funnel, paddle stirrer, and Claisen adapter with low-temperature thermometer and an Nj inlet was charged with chlorophenylmercury (9.39 g, 30 mmol), ethyl bromofluoroacetate (6.61 g, 35.6 mmol), and THF (100 mL). In the addition funnel was prepared a solution of r-BuOK (3.93 g, 35 mmol) in THF (50 mL), precipitated as the alkoxide by addition of r-BuOH (33 mL, ca. 35 mmol). 

Both a-fluorocarboalkoxy phosphon ttsf36,37) and a-fluorocarboalkoxy phosphonium saks(38) can be readily prepared from the commercially available ethyl bromofluoroacetate, or this ester can be readily obtained from the commercially available bromotrifluoroethene by application of the Organic Syntheses(39,) preparation of ethyl chlorofluoroacetate. Subsequent deprotonation of either (1) or (2)... 

Several routes to this class of compounds have been reported, such as (a) crossed Claisen condensation reactions (50-53) (b) acylation of the anion derived from ethyl fluoroacetate (54) or self-condensation of the anion derived from ethyl bromofluoroacetate (55) (c) electrophilic fluorination of the anion of p-ketoesters (56,57) (d) acylation-hydrolysis of fluoroolefins (58) and (e) acylation of fluorine-containing ketene silyl acetals (Easdon, J.C., University of Iowa, unpublished data). The limitations associated with these methods and the success achieved in the alkylation-hydrolysis of a-fluoro phosphorus ylides prompted us to examine acylation-hydrolysis of these a-fluoro ylides as a general route to 2-fluoro-3-oxoesters. 

Somewhat less than the equivalent amount of dry Na-ethoxide added with stirring and cooling at —10 to an ethereal soln. of equimolar amounts of benzophenone and ethyl fluoroacetate, after the addition stirring continued without cooling unless room temp, is exceeded ethyl -fluoro-j -hydroxy-/ , -diphenylpropionate. Y 60%.—If applicable, this method is simpler than the Reformatkii synthesis, which would require ethyl bromofluoroacetate as startg. m. F. e. with lower yields s. V. F. Martynov and M. I. Titov, 7K. 32, 718 (1962) G. A. 58, 6740a. 

Hydrogen bromide converts ethyl chlorofluoroacetate to bromofluoroacetic acid. [55] (equation 39). 

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