An oxidative coupling for the synthesis of arylated quaternary stereocentres and its application in the total synthesis of powelline and buphanidrine
摘要:
Catechol derivatives directly bonded to all-carbon quaternary stereocentres are prevalent in nature. An oxidative coupling strategy for the synthesis of this motif is described. Pivoting on the base-catalysed Michael addition of carbon-centred pro-nucleophiles to in situ generated ortho-benzoquinones, the method is broad in scope, high yielding and provides remarkably simple access to this challenging motif. The application of this methodology in the total synthesis of the crinane-type amaryllidaceae alkaloids (+/-)-powelline and (+/-)-buphanidrine is demonstrated and our efforts towards an enantioselective synthesis described. (C) 2010 Elsevier Ltd. All rights reserved.
Laccase-catalysed α-arylation of cyclic β-dicarbonyl compounds
作者:Jörg Pietruszka、Chuan Wang
DOI:10.1039/c2gc35662g
日期:——
In this protocol we described an environmentally friendly synthesis of α-arylated cyclic β-dicarbonyl compounds employing various catechols as precursors through an oxidation/Michael addition sequence. The process proceeded under the catalysis of a commercially available laccase at room temperature with the use of aerial oxygen as the oxidant affording the products in moderate to excellent yields (36–96%)
A green oxidative coupling reaction of catechols with activemethylenecompounds was achieved using an AlPO4-supported Ru catalyst, where O2 and H2O were used as the ideal oxidant and solvent, respectively. The catalyst is easily separable, reusable and applicable for gram-scale syntheses.