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
<i>Cinchona</i> Alkaloid Catalyzed Enantioselective [4 + 2] Annulation of Allenic Esters and <i>in Situ</i> Generated <i>ortho</i>-Quinone Methides: Asymmetric Synthesis of Functionalized Chromans
作者:Yu-Hua Deng、Wen-Dao Chu、Xiang-Zhi Zhang、Xu Yan、Ke-Yin Yu、Liang-Liang Yang、Hanmin Huang、Chun-An Fan
DOI:10.1021/acs.joc.7b00370
日期:2017.5.19
A novel enantioselective [4 + 2] annulation of the allenoates having a unique positive ortho-effect with in situ generated ortho-quinone methides has been developed under the catalysis of Cinchonaalkaloid. This chiral amine-catalyzed reaction provides an alternative route to asymmetric catalytic construction of synthetically interesting, highly functionalized chiral chromans in good to excellent
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.
Michael Additions of Highly Basic Enolates to <i>ortho</i>-Quinone Methides
作者:Robert S. Lewis、Christopher J. Garza、Ann T. Dang、Te Kie A. Pedro、William J. Chain
DOI:10.1021/acs.orglett.5b00972
日期:2015.5.1
which ketone or esterenolates and ortho-quinone methides (o-QMs) are generated in situ in a single reaction flask from silylated precursors under the action of anhydrous fluoride is reported. The reaction partners are joined to give a variety of β-(2-hydroxyphenyl)-carbonyl compounds in 32–94% yield in a single laboratory operation. The intermediacy of o-QMs is supported by control experiments utilizing