Trifluoroethyl acetate, hydrolysis

Kutsuna, S., Chen, L., Ohno, K., Tokuhashi, K., and Sekiya, A. Henry s law constants and hydrolysis rate constants of 2,2,2-trifluoroethyl acetate and methyl trifluoroacetate, Atmos. Environ., 38(5) 725-732, 2004. 

Fig. 10. Rates of imidazole-catalyzed ester hydrolysis as a function of the rate of alkaline hydrolysis nucleophilic reactions of acetates, general base catalysis of acetates, a general base catalysis of methyl and ethyl esters, o (ionic strength 1-0 25°). Trifluoroethyl acetate measured with N-methylimidazole. From Kirsch and Jencks (1964a). Reproduced with permission of the American Chemical Society. (> = NOAc = acetoxime acetate).

A number of selective acylations and deacylations catalysed by enzymes, especially by lipases in organic solvents, have been reported. Methyl pentofuranosides could be selectively acetylated at 0-5 on a preparative scale by use of a lipase and 2,2,2-trifluoroethyl acetate as acyl donor in THF, while selective hydrolysis could be effected at the primary positions of peracetylated methyl pentofuranosides and hexopyranosides, and at the anomeric centres of peracetylated D-rilao- and D-xylo-furanoses and -pyranoses with lipases in aqueous DMF. ° Methyl -D-glucopyranoside, D-mannose, and 2-acetamido-2-deoxy-D-mannose were all substituted selectively at 0-6 by lipase-mediated... 

In a similar context, 6-18F-3,4-dihydroxyphenylalanine (6-18F-DOPA) was synthesized by direct fluorination of L-3-(3-hydroxy-4-pivaloxyphenyl)alanine (ra-P-DOPA) with Ac018F in acetic acid resulting in the 2- and 5-18F isomers. Hydrolysis of the reaction mixture in hydrochloric acid followed by HPLC separation gave 6-18F-DOPA (equation 23)44. Another application of Ac018F was reported in the synthesis of a trimethyl tin precursor of 2-oxoquazepam, 7-chloro-1 -(2,2,2-trifluoroethyl)-1,3--dihydro-5-(2-fluorophenyl)-2//-l,4-benzodiazepin-2-one, a benzodiazepine agonist, and its conversion to [18F]-2-oxoquazepam by reaction with AcQ18F (equation 24)45. 

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