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The Quest for New Mild and Selective Modifications of Natural Structures: Laccase‐Catalysed Oxidation of Ergot Alkaloids Leads to Unexpected Stereoselective C‐4 Hydroxylation
Author(s) -
Chirivì Cosimo,
Fontana Gabriele,
Monti Daniela,
Ottolina Gianluca,
Riva Sergio,
Danieli Bruno
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201201076
Subject(s) - hydroxylation , stereoselectivity , chemistry , stereochemistry , substituent , organic chemistry , catalysis , enzyme
Abstract Laccase‐catalysed oxidation of ergot alkaloids in the absence of chemical mediators allowed the unexpected isolation of the mono‐hydroxylated derivatives of compounds 2 – 7 . Structure determination by NMR techniques clearly indicated that hydroxylation took place at the C‐4 benzylic position. Quite notably, the proposed protocol allowed, for the first time, functionalisation at the C‐4 position of the ergoline skeleton. Depending on the absence or on the presence of a C‐10 α‐methoxy substituent, hydroxylation was either stereoselective (furnishing C‐4α OH derivatives) or gave rise to a C‐4α/C‐4β OH mixture in a 2:1 ratio, respectively.