AXIALLY CHIRAL BIS(ALPHA-AMINO ACID)S AND THEIR DEAMINO ANALOGS - SYNTHESIS AND CONFIGURATIONAL ASSIGNMENT

The axially chiral bis(alpha-amino acid)s cis-2 and trans-2 as possibl e building blocks for polymeric structures of novel type of helicity w ere prepared. Their configuration has been determined by NMR spectrosc opy and, in the case of the trans-isomer, confirmed by single-crystal X-ray diffraction. Analogous pair of stereoisomeric diacids cis-3 and trans-3, devoid of the amino groups, was also prepared and their confi guration assigned. The observed differences in the NMR spectra of cis- and irans-isomers of 2 and 3 are discussed from the viewpoint of their different symmetry properties.