Concise Synthesis of the Multiply Oxygenated ABC-Ring System of the Dihydro-β-agarofurans
摘要:
The multiply oxygenated ABC-ring system of the dihydro-beta-agarofurans was synthesized by employing two highly stereoselective reactions. The quinidine-catalyzed Diels-Alder reaction between a chiral dienophile and 3-hydroxy-4-methyl-2-pyrone simultaneously installed the C2-stereogenic center and two contiguous tetrasubstituted carbon centers (C5 and C10) of the A-ring. After 12 additional transformations, the aldol reaction of the resulting spiral AC-ring cyclized the B-ring with stereoselective introduction of the C7- and C8-centers.
Asymmetric Diels−Alder Reactions of 2-Pyrones with a Bifunctional Organic Catalyst
作者:Yi Wang、Hongming Li、Yong-Qiang Wang、Yan Liu、Bruce M. Foxman、Li Deng
DOI:10.1021/ja070859h
日期:2007.5.1
The reactions of 2-pyrones with electron-deficient dienophiles constitute a synthetically useful class of Diels−Alder reaction. By exploring cinchona alkaloid-derived organic molecules as acid−base bifunctionalcatalysts, we successfully developed the first highly enantioselective and diastereoselective catalytic Diels−Alder reaction with 2-pyrones. Furthermore, we demonstrated the possibility of using
Synthesis of Highly Substituted Phenols and Benzenes with Complete Regiochemical Control
作者:Xiaojie Zhang、Christopher M. Beaudry
DOI:10.1021/acs.orglett.0c02157
日期:2020.8.7
Substitutedphenols are requisite molecules for human health, agriculture, and diverse synthetic materials. We report a chemical synthesis of phenols, including penta-substituted phenols, that accommodates programmable substitution at any position. This method uses a one-step conversion of readily available hydroxypyrone and nitroalkene starting materials to give phenols with complete regiochemical
Regioselective Synthesis of Benzofuranones and Benzofurans
作者:Xiaojie Zhang、Christopher M. Beaudry
DOI:10.1021/acs.joc.1c00341
日期:2021.5.7
preparation of the benzofuranones with programmable substitution at any position. Complex substitution patterns are readily created. The substituted benzofuranones can be converted to substituted benzofurans.
Enantiodivergent [4+2] Cycloaddition of Dienolates by Polyfunctional Lewis Acid/Zwitterion Catalysis
作者:Vukoslava Miskov‐Pajic、Felix Willig、Daniel M. Wanner、Wolfgang Frey、René Peters
DOI:10.1002/anie.202009093
日期:2020.11.2
Different catalysis concepts have been reported, including dienophile activation by Lewis acids or H‐bond donors and diene activation by bases. Herein we report a new concept, in which an acidic prodiene is acidified by a Lewis acid to facilitate deprotonation by an imidazolium–aryloxide entity within a polyfunctional catalyst. A metal dienolate is thus formed, while an imidazolium–ArOH moiety probably
Enantioselective Diels−Alder Reaction of Simple α,β-Unsaturated Ketones with a Cinchona Alkaloid Catalyst
作者:Ravi P. Singh、Keith Bartelson、Yi Wang、Heng Su、Xiaojie Lu、Li Deng
DOI:10.1021/ja078251w
日期:2008.2.1
The simple α,β-unsaturated ketones and 2-pyrones are readily available and synthetically important dienophiles and dienes, respectively, for Diels−Alder reactions. However, both prove to be challenging substrates for catalytic asymmetric Diels−Alder reactions. By exploring a new catalysis strategy featuring cooperative catalysis with readily available cinchona catalysts, an unprecedented asymmetric