The quincyte pigments: Fossil quinones in an eocene clay mineral
作者:William G. Prowse、Katherine I. Arnot、Josef A. Recka、Ronald H. Thomson、James R. Maxwell
DOI:10.1016/s0040-4020(01)80947-9
日期:1991.1
An unusual series of quinone pigments in a pink Eocene (c. 45x10(6) yr) sepiolite (quincyte, France) has been characterised by spectroscopy. The structure of the major pigment (c. 75% of total), 2,8-di-isopropyl-peri-xanthenoxanthene-4,10-quinone, was confirmed by synthesis. Spectroscopy revealed six minor related components with various oxygenated C-2 substituents (C1-C3) and, generally, a C-8 isopropyl group. Although the origin of the pigments is unknown, they (or their precursors) appear to have been biosynthesised by the acyl-malonate pathway.
Chirality Transfer from the Oxidative Dearomatization of Axially Chiral Binols with Oxone under Mild Conditions
作者:Antonio Urbano、Sara Vallejo、María J. Cabrera-Afonso、Elena Yonte
DOI:10.1021/acs.orglett.0c02194
日期:2020.8.7
Easily accessible axially chiral substituted binols (95 to >99% ee) undergo an oxidative dearomatization process with the system Oxone/NaHCO3/acetone, under mild conditions, to afford pentacyclic hemiacetalic cis-diols (94 to >99% ee), bearing two new stereogenic centers, through an efficient axial-to-central chirality transfer.
Enantioselective Oxidative Homocoupling and Cross-Coupling of 2-Naphthols Catalyzed by Chiral Iron Phosphate Complexes
作者:Sachin Narute、Regev Parnes、F. Dean Toste、Doron Pappo
DOI:10.1021/jacs.6b11198
日期:2016.12.21
Novel chiral ironphosphatecomplexes were prepared as catalysts for asymmetric oxidative coupling reactions. These catalysts were applied for the synthesis of enantio-enriched C1- and C2-symmetric BINOLs, in which the 3 and 3' positions are available for chemical modifications. It was proposed that the reaction takes place via an oxidative radical-anion coupling mechanism. A destructive BINOL racemization