A fluorine anion-mediated diphosphination of ortho-quinone methide precursors (2-(chloromethyl)silyloxybenzenes) with diphosphines has been developed. The reaction proceeds smoothly under mild conditions (CH2Cl2 solvent, 0 °C) to form the corresponding 2-(phosphinomethyl)oxyphosphinobenzenes, which are potential bidentate ligands in metal catalysis. Additionally, some mechanistic investigations are
N-Heterocyclic carbene-catalyzed enantioselective annulations: a dual activation strategy for a formal [4+2] addition for dihydrocoumarins
作者:Anna Lee、Karl A. Scheidt
DOI:10.1039/c4cc09590a
日期:——
A highly efficient asymmetric formal [4+2] annulation for the synthesis of dihydrocoumarins has been developed via an in situ activated NHC catalysis. Both electrophilic and nucleophilic species are generated in situ simultaneously whereby acyl imidazoles facilitated rapid formation of an NHC-enolate intermediate to afford the [4+2] dihydrocoumarin adducts.
Formal [4 + 1] cycloaddition of o-quinone methides: facile synthesis of dihydrobenzofurans
作者:Xiantao Lei、Chun-Huan Jiang、Xiaoan Wen、Qing-Long Xu、Hongbin Sun
DOI:10.1039/c4ra17003b
日期:——
An efficient and straightforward method for the rapid synthesis of 2-substituted dihydrobenzofurans has been developed via reaction of sulfur ylides with o-quinonemethides (o-QMs), which were generated under mild conditions. The products could be obtained in excellent yields with various kinds of sulfur ylides.
A formal intermolecular [4 + 1] cycloaddition reaction of 3-chlorooxindole and <i>o</i>-quinone methides: a facile synthesis of spirocyclic oxindole scaffolds
作者:Chao Lin、Qi Xing、Honglei Xie
DOI:10.1039/d1ra01086g
日期:——
Herein, we developed an efficient and straightforward method for the rapid synthesis of spirocyclic oxindole scaffolds via the [4 + 1] cyclization reaction of 3-chlorooxindole with o-quinone methides (o-QMs), which were generated under mild conditions. The products could be obtained in excellent yields with numerous types of 3-chlorooxindole. This methodology features mild reaction conditions, high
Nucleophilic Acylation of <i>o-</i>Quinone Methides: An Umpolung Strategy for the Synthesis of α-Aryl Ketones and Benzofurans
作者:Anita E. Mattson、Karl A. Scheidt
DOI:10.1021/ja068189n
日期:2007.4.1
The synthesis of alpha-aryl ketones is accomplished by the direct nucleophilic acylation of o-quinone methide electrophiles. In this process, two reactive intermediates, carbonyl anions and o-quinone methides, are generated in one flask upon treatment of the corresponding thiazolium carbinols and silyl protected phenols with a soluble fluoride source. These intermediates then undergo productive addition reactions to afford the desired alpha-aryl ketone adducts. This new strategy has been applied to a short synthesis of the natural product demethylmoracin I.