Issue in Honor of Prof. Rod Rickards ARKIVOC 2004 (x) 152-165
Absolute stereochemistry of fungal metabolites: icterinoidins A1 and B1, and atrovirins B1 and B2#
Melvyn Gill* and Peter M. Morgan
School of Chemistry, The University of Melbourne, Parkville, 3010, Australia E-mail:
[email protected]
Dedicated, with respect and gratitude, to Professor Rodney W. Rickards in celebration of his 70th birthday (received 31 May 04; accepted 01 Jul 04; published on the web 08 Jul 04)
Abstract
The absolute stereochemistry at the C 3 (and C 3', where appropriate) chiral centre(s) in the coupled dihydroanthracenones, the icterinoidins A1 and B1 and atrovirin B2 (from Dermocybe icterinoides), is deduced by application of the 'syn-anti rule', which relies on an empirical relationship between the sign of the Cotton effect couplet centred close to 275 nm in the CD spectrum and the chemical shift of the enantiotopic methylene protons at C 4 in the 1H NMR spectrum of these pre-anthraquinones. The conclusions also allow assignment of central stereochemistry to atrovirin B1 (from Cortinarius atrovirens). In addition, we have applied Steglich's kinetic resolution method to confirm the (P)-axial configuration of icterinoidin B1, previously deduced by using Nakanishi's 'exiton chirality' method.
Keywords: Fungal pigments, dihydroanthracenone dimmers, icterinoidins A1, B1, atrovirin B2, stereochemistry, atropisomers, Dermocybe icterinoides, chemotaxonomy
Introduction
In an earlier paper in this series1 we described, inter alia, the isolation and structural elucidation of two new atropisomeric 5,5'-coupled dihydroanthracenone–anthraquinones, the icterinoidins A1 (1) and B1 (2), atrovirin B2 (3), a diastereoisomer of the known atrovirin B1 (4)2 (no central stereochemistry yet implied), and the well known orange pigment (P)-(+)-skyrin (5)3 from the
#Part 73 in the series 'Pigments of Fungi'; for Part 72 see: Donner, C. D.; Gill, M.; Tewierik, L. Molecules, 2004, 9,
498. ISSN 1424-6376 Page 152 ©ARKAT USA, Inc
