ISSN:
0009-2940
Schlagwort(e):
Resolution by crystallization of diastereoisomeric salts
;
Perfluoropropylene oxide
;
Trifluoropyruvate
;
Capillary GC determination of ratios of enantiomers
;
Cyclodextrine-derived GC columns
;
Determination of the sense of chirality by chemical correlation
;
pKs of 3,3,3-trifluoro-2-hydroxypropanoic and 4,4,4-trifluoro-3-hydroxybutanoic acid
;
Chemistry
;
Inorganic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Simple Access to (R)- and (S)-3,3,3-Trifluorolactic Acid and to (R)- and (S)-(Trifluoromethyl)oxiraneEthyl trifluoropyruvate (from hexafluoropropylene oxide) is reduced by NaBH4 to rac-trifluorolactic acid which is resolved on a 100-g scale by salt formation with (R,R)- and (S,S)-2-amino-1-phenyl-1,3-propanediol (readily available intermediates of industrial chloroamphenicol synthesis). The enantiomerically pure trifluorolactic acids (〉99% ee by GC analysis on cyclodextrin columns) are converted into (R)- and (S)-(trifluoromethyl)oxirane in an overall yield of 73% by the following steps: esterification, THP protection of the OH group, LAH reduction and mesylation to the 2-THP-protected mesylate of 3,3,3-trifluoro-1,2-propanediol, and one-pot deprotection (Dowex 50) and cyclization (NaOCH2CH2OH) in ethylene glycol. The enantiomeric purity of the oxirane (b.p. 39=C, isolated on a 10-g scale) was determined by GC to be 〉99%. Possible synthetic targets are mentioned which should be accessible in enantiomerically pure form from the (trifluoromethyl)oxirane described here.
Zusätzliches Material:
2 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/cber.19921251227
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