The structures of some azopigments obtained by diazotization of conjugated and unconjugated bile pigments with diazotized ethyl anthranilate were studied by mass spectrometry. The alpha(0)-azopigments derived from rat bile and human bile were shown to be identical (t.l.c. and mass spectra) with azobilirubin derived from unconjugated bilirubin. The presence of two methyl vinyl isomers (Ia) and (...

Three new natural coumarin substances 1, 2 and 3 (derivatives of 2',2'-dimethyl-3',4'-dihydroxydihydropyrano-5',6':6,7-coumarin) were isolated from the roots and fruits of Peucedanum arenarium W.K. On the basis of the spectral data from UV, IR, and NMR spectra of coumarin 1, named peuarenarine, it was assumed, that, it is an ester of 2',2'-dimethyl-3',4'-dihydroxy-dihydropyrano5',6' :6,7-coumar...

A new enantioselective total synthesis of pachastrissamine (jaspine B) was achieved from a known alpha,beta-unsaturated aldehyde by utilizing Córdova's asymmetric epoxidation as the chirality-inducing step. The 2,3-cis stereochemistry of pachastrissamine was established via intramolecular epoxide ring opening of a gamma,delta-epoxy-alpha,beta-unsaturated ester intermediate coupled with oxy-Mich...