ENANTIOSELECTIVE RECOGNITION OF HISTIDINE AND LYSINE ESTERS BY PORPHYRIN CHIRAL CLEFTS AND DETECTION OF AMINO-ACID CONFORMATIONS IN THE BOUND-STATE

Resolution of the bisporphyrin Troger's base analogue 1 affords homochiral clefts that tightly bind histidine esters in 80-86% e.e. and lysine benzyl ester in 48% e.e.; the histidine esters are bound in fixed conformations that can be readily detected by H-1 NMR spectroscopy as a result of the large dispersion of proton resonances by the ring currents of the two porphyrins.