HELICALLY SHAPED BILIRUBINS - NATURAL OPTICAL-ACTIVITY AND CHEMICAL CORRELATION OF M AND P BACKBONE HELICITY WITH BILIVERDINS

The natural optical activity of 2,18-bridged helically shaped bilirubi ns 2 and an unambigous chemical correlation of the M and P backbone he licity with the corresponding biliverdins 1 is reported. Complete reso lution of the four component stereoisomeric mixture of (M,1'S), (M,1'R ), (P,1'S) and (P,1'R) chirality was performed at the biliverdin stage 1. The optical activity of compounds is discussed in terms of the dia gnostic value of CD spectra in the conformational analysis of non-rest ricted bilirubins.