2,2-chlorofluoroacetic ester

The conversion of primary alcohols into chlorofluoroacetic esters is referred to in Chapter 7, while the formation of the unusual L-rhamnopyranosyl esters (22) and (23) is dealt with in Chapter 3. The advantages of using trifluoro-acetyl derivatives in the m.s. of methyl hexopyranosides is referred to in Chapter 24. ... 

ETHYL CHLOROFLUOROACETATE (Acetic acid, chlorofluoro-, ethyl ester)... 

The migration order of groups in the Baeyer-Villiger oxidation is valid also for chlorofluoro-alkyl ketones, in which the isopropyl group specifically migrates to give the isopropyl ester of chlorofluoroacetic acid (Tabic 11).195... 

A general route to acid fluorides, chlorides, bromides and iodides is provided by the reaction of enol esters, such as isopropenyl esters, with the appropriate hydrogen halide (equation 18). Phthalic acid dichloride in the presence of chlorosulfonic acid has been proposed as a reagent for the conversion of carboxylic esters to acid chlorides in high yield, as is shown in equation (19) for the cleavage of the ethyl ester of chlorofluoroacetic acid. °... 

The reagent reacts with O-isopropylidene sugars to give chlorofluoroacetates 8 Formation of esters was originally believed to be due to the presence of water, but in the present case esters were still obtained under strictly anhydrous conditions. 

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)... 

Alkylation at phosphorus under Michaelis-Becker conditions has been widely practised. Triethyl phosphonoacetate, and also other phosphonoacetic esters, have often been made this chlorine is selectively removed from esters of chlorofluoroacetic acid... 

The reaction of carboxylic acid esters with a mixture of chlorosulfonic acid and phthaloyl chloride affords a useful one-step procedure for the conversion of esters directly into the acyl chlorides. For instance, heating an equimolar mixture of chlorofluoroacetate 99, phthaloyl chloride 100 and chlorosulfonic acid afforded chlorofluoroacetyl chloride 101 (88% yield) (Equation 41). ... 

Carboxylic acid esters by heating with an equimolar mixture of phthaloyl chloride and chlorosulfonic acid at 70-250 C gave good yields of the corresponding acid chlorides. Thus, ethyl chlorofluoroacetate, by heating with the mixture at 180 °C, afforded chlorofluoroacetyl chloride (88% yield), but when the ester was heated with chlorosulfonic acid alone the yield of the acid chloride was reduced to 50%. The procedure provides a valuable synthetic route for the direct conversion of carboxylic acid esters into the corresponding acid chlorides (see Chapter 5, p 167). ... 

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