Propentdyopents [5-(2-oxo-2H-pyrrol-5-ylmethylene)pyrrol-2(5H)-ones] and related compounds. Part 2. The Z⇄E photoisomerisation of pyrromethenone systems
The Z⇄E photoisomerisation of four α-unsubstituted pyrromethenones which are potential precursors of alkanol–propentdyopent adducts is studied using a direct n.m.r. spectroscopic approach in CD3OD–CDCl3. Chemical-shift assignments are made with the help of n.O.e. and decoupling experiments. For the polyalkylpyrromethenones the photostationary state contains ca. 25% of the E isomer: a system with a
BONNETT, RAYMOND;HAMZETASH, DARIUSH;VALLES, MARIA ASUNCION, J. CHEM. SOC. PERKIN TRANS.,(1987) N 6, 1383-1388
作者:BONNETT, RAYMOND、HAMZETASH, DARIUSH、VALLES, MARIA ASUNCION
DOI:——
日期:——
LARGE SCALE, EFFICIENT SYNTHESIS OF 9-UNSUBSTITUTED DIPYRRINONE
作者:Qingqi Chen、Tianyu Wang、Yi Zhang、Qiuan Wang、Jinshi Ma
DOI:10.1081/scc-120003151
日期:2002.1
ABSTRACT 9-Unsubstituted dipyrrinone 8, the useful precursor for the synthesis of biliverdins, bilirubins, and other bile pigments, was synthesized in largescale and high yield starting from acetaldehyde and nitroethane in eight steps with overall yield 10%. The key intermediate 3,4-dimethyl-2-ethoxycarbonylpyrrole 3 was synthesized via Zard–Barton's method in high yield.