Synthesis of 3,3,4,4-tetrafluoro-1,2-bis(imino)cyclobutanes: A cyclic version of fluorinated α-diimines

Selective Defluorination Approach to N-Cbz-3,3-difluoro-2-difluoromethylenepyrrolidine and Its Application to 3,3-Difluoroproline Dipeptide Synthesis

“…The Mg-promoted defluorination of trifluoromethyl imines and ketones converting a trifluoromethyl group to a difluoromethylene group has been systematically studied. − Recently, the defluorination protocol has been applied to the selective defluorination of imine 1 to 2 , which was transformed subsequently to trifluoroalanine dipeptides, where the difluoromethylene group of 2 was chemically modified to a carboxamide group, and thus the peptide synthesis involved a new entry to amide bond construction totally different from the conventional condensation of two kinds of amino acids . On this basis, it is interesting to see another utilization of 2 , in which the difluoromethylene group would become the difluoromethylene moiety of difluoroproline and the trifluoromethyl group could be modified to the carbamide part of difluoroproline dipeptides.…”