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Redox‐Neutral Syntheses and Electrochemical Studies of 10‐Bromo‐Substituted Light‐Stable Antivitamin B 12 Candidates
Author(s) -
Brenig Christopher,
Mosberger Leila,
Baumann Katja,
Blacque Olivier,
Zelder Felix
Publication year - 2021
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.202100067
Subject(s) - chemistry , electrochemistry , redox , cobalamin , yield (engineering) , bromine , cleavage (geology) , photochemistry , medicinal chemistry , inorganic chemistry , organic chemistry , electrode , biochemistry , materials science , geotechnical engineering , fracture (geology) , engineering , metallurgy , vitamin b12
This publication describes the straightforward and redox‐neutral synthesis of 10‐bromophenylethynylcobalamin and its facile conversion to 10‐bromoaquacobalamin. In this approach, the phenylethynyl ligand acts as convenient light‐stable protecting group that is removed in quantitative yield under acidic conditions. The proteolytic cleavage at pH 2.0 was studied under pseudo ‐first‐order conditions and is 1.5 times slower than that of phenylethynylcobalamin with a hydrogen instead of a bromine at C(10). Preliminary electrochemical studies of organometallic ethynyl‐Cbls (Cbl=cobalamin) are reported for the first time. A reduction potential Ep ( C o I I I/ C o I )of −0.94 V vs . Ag/AgCl was determined for the Co III /Co I reduction of 10‐bromophenylethynylcobalamin. The positive potential shift of 180 mV compared to phenylethynylcobalamin is in agreement with earlier electrochemical studies of related cyanocobalamins.