Coenzyme models. Part 45. Synthesis of atropisomeric flavins and their novel redox-induced racemisation

Seiji Shinkai, Hideki Nakao, Itsuko Kuwahara, Megumi Miyamoto, Toshiro Yamaguchi, Osamu Manabe

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Seven (5-carba)isoalloxazines with restricted rotation about the C(1′)-N(10) single bond were synthesized for the first time. They were optically resolved by a liquid chromatographic method. Six of these atropisomers (92.1-100% enantiomeric excess) (e.e.) did not racemise thermally (at 70°C) or by visible light irradiation (at 30°C). On the other hand, the (5-carba)isoalloxazines with a 2′-substituted phenyl group or a naphthyl group at N(10) racemised invariably when they were reduced to 1,5-dihydro forms [by four different reducing agents including photoreduction with ethylene diamine tetra-acetic acid (EDTA)]. The kinetic studies confirm that the racemisation process consists of slow, rate-determining reduction of chiral (5-carba)isoalloxazines followed by rapid rotation of the C(1′)-N(10) single bond. The easy rotation in the reduced state is due to conversion of the 'planar' oxidised forms into the 'bent' reduced forms. These (5-carba)isoalloxazines are novel examples for atropisomers with a C-N axis, the rotation of which is induced only by the redox reaction.

Original languageEnglish
Pages (from-to)313-319
Number of pages7
JournalJournal of the Chemical Society, Perkin Transactions 1
Issue number2
DOIs
Publication statusPublished - 1988
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

Fingerprint Dive into the research topics of 'Coenzyme models. Part 45. Synthesis of atropisomeric flavins and their novel redox-induced racemisation'. Together they form a unique fingerprint.

  • Cite this