Electroorganic syntheses of macrocyclic lactones mediated by vitamin B12 model complexes: Part 17. Hydrophobic vitamin B12

Hisashi Shimakoshi, Aki Nakazato, Takashi Hayashi, Yoshimitsu Tachi, Yoshimitsu Naruta, Yoshio Hisaeda

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

The electrolyses of bromoalkyl acrylates were carried out in N,N-dimethylformamide in the presence of a catalytic amount of heptamethyl cobyrinate perchlorate under various reaction conditions. A large-membered cyclic lactone was obtained in a moderate yield. A photo-sensitive intermediate having a cobalt-carbon bond formed during the electrolysis has been characterized using electronic and electrospray ionization mass spectroscopies in the dark. The formation of a cyclic lactone was inhibited by the addition of the spin-trapping reagent, α-phenyl N-(t-butyl)nitrone. Based on various spectroscopic results, the electrolysis proceeds as follows: the Co(II) complex as a catalyst is electrochemically reduced to the Co(I) species, and the corresponding alkylated complex is generated by the reaction of the supernucleophilic Co(I) species with a bromoalkyl acrylate. The alkylated complex is subsequently decomposed to form the substrate radical, and the intramolecular addition of the radical affords the cyclic product. During the catalytic reaction, the cobalt complex repeatedly acts as a mediator.

Original languageEnglish
Pages (from-to)170-176
Number of pages7
JournalJournal of Electroanalytical Chemistry
Volume507
Issue number1-2
DOIs
Publication statusPublished - Jul 13 2001

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Chemical Engineering(all)
  • Electrochemistry

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