2-TRIFLUOROMETHYL-SUBSTITUTED AMINO-ACIDS .19. 2-TRIFLUOROMETHYL ALPHA-AMINO-ACID ESTERS, BUILDING-BLOCKS FOR TRIFLUOROMETHYL-SUBSTITUTED UREAS, THIOUREAS AND OTHER POTENTIAL BIOLOGICAL ACTIVE STRUCTURES

The preparative value of trifluoromethyl-substituted building blocks i ncreases with the number of additional functionalities present. 2-Trif luoromethyl alpha-amino acid esters 2 represent readily available star ting materials, excellently suited for the introduction of the biologi cally interesting trifluoromethyl group into a variety of classes of c ompounds, like ureas 4 and thioureas, acylureas 5 and acylthioureas 12 , imidazolidin-2,4-diones 8 and imidazolidin-4-on-2-thiones 11 as well as 2-isocyanatoalkanoic acids 13. Via the latter Fmoc-2-trifluorometh yl alpha-amino acid 16a can be readily prepared.