APPLICATIONS OF MTPA (MOSHER) AMIDES OF SECONDARY-AMINES - ASSIGNMENTOF ABSOLUTE-CONFIGURATION IN CHIRAL CYCLIC AMINES

Mosher's MTPA (methoxy(trifluoromethyl)phenylacetyl) technology is app lied to the assignment of absolute configuration of several synthetic and natural chiral amines. The substrates are cyclic, secondary amines . The resulting amides usually contain significant populations of two rotamers, readily distinguished by H-1 NMR spectroscopy. Thus, two com plementary sets of Delta delta values are obtained from a single analy sis, thereby enhancing the power of the method. A strategy for the MTP A derivatization of (the N-methyl tertiary amine in) the tropane alkal oid, cocaine, is also described. The exceptionally large Delta delta v alues observed for these MTPA amides make this a valuable and reliable method for assignment of amine configuration (even in some cases wher e only one diastereomeric MTPA amide is readily available).