Methyl Dichlorofluoroacetate

[431-44-77]  · C3H3Cl2FO2  · Methyl Dichlorofluoroacetate  · (MW 160.96)

(Reformatsky-type reactions with aldehydes to give 2-fluoroenoates)

Physical Data: bp 82-85 °C/0.5 mmHg.

Solubility: usually used in polar solvents (acetone)

Analysis of Reagent Purity: satisfactory microanalytical data reported.1

Preparative Method: prepared in 65% yield by reaction of methyl trichloroacetate and Antimony(III) Chloride in the presence of Bromine.1,2

The methyl ester of dichlorofluoroacetic acid is a useful reagent in Reformatsky-type reaction with aldehydes (eq 1).2 This procedure allows preparation of 2-fluoroenoates (1) in synthetically useful yields; (Z)-isomers are formed in high preponderance (&egt;93% (Z)-isomer obtained). In the absence of molecular sieves the reaction does not occur.

The use of anhydride sources as an alternative to the simple acetyl anhydride employed in eq 1 has been reported as an improvement to this method (Table 1 and eq 2).3 The same report describes several reactions in which the previously claimed high selectivity for the (Z)-isomer in the alkenation reaction is not observed; up to 40% (E)-alkene is obtained.

1. Gryszkiewicz-Tochimowski, E.; Sporzynski, A.; Wnuk, J. RTC 1947, 66, 419.
2. Ishihara, T.; Kuroboshi, M. CL 1987, 1145.
3. Allmendinger, T. T 1991, 47, 4905.

Joseph Sweeney

University of Bristol, UK

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