SynopsisFourier transform ir vibrational circular dichroism (VCD) spectra in the amide I' region of poly(L-lysine) in D,O solutions have confirmed the existence of three distinct conformational states F d an unordered conformational state in this homopolypeptide. Characteristic VCD spectra are presented for the right-handed a-helix, the antiparallel P-sheet, an extended helix conformation previously referred to as the so-called "random coil," and a completely unordered conformation characterized by the absence of any amide I' VCD. VCD for the antiparallel P-sheet in solution and the unordered chain conformation are presented for the first time. Each of the four different VCI) spectra is unique in appearance and lends weight to the view that VCD has the potential to become a sensitive new probe of the secondary structure of proteins in solution.

The absolute configuration of the norlignan (+)-nyasol was determined to be S by comparison of the experimental vibrational circular dichroism data with first-principle calculations taking into account the eight lowest energy conformations. The established absolute configuration of (+)-nyasol enables establishment of the absolute configuration of (-)-hinokiresinol, which is concluded to be S. A total synthesis and resolution of hinokiresinol has been performed to resolve the conflicting reports of the coupling constant of the vinylic protons of the disubstituted double bond in this molecule. Racemic hinokiresinol was resolved. Both enantiomers possess the same antiplasmodial activity.

The erythro isomer of 1-naphthyl-1-(2-piperidyl)methanol 4, an efficient chiral modifier for asymmetric heterogeneous hydrogenation, was obtained as the major isomer (95%) in two steps while the threo isomer can be obtained as the major isomer (67%) in three steps. erythro-4 and threo-4 were resolved on a CHIRALCEL OD-RH column. It has been shown by VCD that the diastereomer determined as the erythro by NMR was indeed the erythro and that the first eluted (-)-enantiomer on CHIRALCEL OD-R or -RH columns has the (1R,2S) configuration. The VCD studies identify the presence of at least five conformers in CDCl(3) solution. Moreover, this (-)-(1R,2S) absolute configuration found by VCD is consistent with the expected stereo-outcome of catalytic hydrogenation of pyruvate into lactate, which supported the (+)-(1S,2R) assignment.