| Abstract
| - Efficient synthesis of optically pureα-(fluoroalkyl)-β-sulfinyl enamines has been achieved byaza-Wittig reaction of triphenyliminophosphoranes with the correspondingα-fluorinated-α‘-sulfinylketones. The title compounds 3,4 showed anoverwhelming preference for the Zstereochemistryof the enamine form. Their general reactivity has been studied.The reaction with someelectrophiles (i.e. benzyl chloroformate and benzyl andallyl bromide) occurs at the nitrogen atomproviding the corresponding N,N-disubstitutedenamines. Nucleophiles add smoothly to C-2: heteroatom-centered nucleophiles like methanol, ammonia, and thiophenolafford gem-disubstitutedderivatives under thermodynamic control, while a C-centerednucleophile like nitromethane addsin irreversible fashion. The hydride- and deuteride-promotedreduction of 3,4 to theN-Cbz-protected(14) and N-unprotected (15)α-fluorinated-α‘-sulfinyl amines has been studied. Hydrideadditionwas stereoselective, while low stereoselection was obtained with theother tested nucleophiles.Desulfurization of the optically pure 1,1,1-trifluoro-3-sulfinylamine 15a afforded(R)-1-(trifluoromethyl)ethylamine 17. The Pummerer rearrangement of14 occurs in an unusual nonoxidativeway affording the sulfenamide 24, that readily provided(R)-(2-H)- and -(2-D)-3,3,3-trifluoroalaninol(19) and (R)-3,3,3-trifluoroalanine(22).
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