Heterodiene cycloadditions: Preparation and transformations of some substituted pyrano[4,3-b][1]benzopyrans
作者:Simon J. Coutts、Timothy W. Wallace
DOI:10.1016/s0040-4020(01)85668-4
日期:1994.1
Heterodienecycloadditions of 4-oxo-4H-1-benzopyrans with formyl, acetyl, or carboxyl substituents at C-3 to 1-alkoxy- or 1,1-dialkoxyalkenes produce 3-alkoxy- or 3,3-dialkoxy-4,4a- dihydropyrano[4,3-b][1]benzopyran-10-ones which are capable of a variety of selective transformations, including acid-induced epimerisation and/or retro-cycloaddition, reduction, hydrolysis and alcoholysis, in some cases
4-氧代-4 H -1-苯并吡喃在C-3处具有甲酰基,乙酰基或羧基取代基的异二烯环加成反应会生成3-烷氧基-或3,3-二烷氧基-4, 4a-二氢吡喃并[4,3- b ] [1]苯并吡喃-10-酮,在某些情况下,能够在多种条件下进行多种选择性转化,包括酸诱导的差向异构和/或逆环加成,还原,水解和醇解非常温和的条件。
Nett asymmetric conjugate addition of a recyclable acetic ester enolate equivalent
作者:Timothy W. Wallace、Ian Wardell、Ke-Dong Li、S. Richard Challand
DOI:10.1039/c39910001707
日期:——
Heterodiene cycloadditions of 3-formyl chromone to ketene acetals derived from C2-symmetric 1,2-diarylethane-1,2-diols are diastereoselective; methanolysis of the cycloadducts derived from (S,S)-hydrobenzoin releases optically enriched methyl 3,4-dihydro-4-oxo-2H-1-benzopyran-2-ylacetate and the optically pure 1,2-diol.
Helical Multi‐Coordination Anion‐Binding Catalysts for the Highly Enantioselective Dearomatization of Pyrylium Derivatives
作者:Theresa Fischer、Julia Bamberger、Melania Gómez‐Martínez、Dariusz G. Piekarski、Olga García Mancheño
DOI:10.1002/anie.201812031
日期:2019.3.4
A general and highlyenantioselective synthesis of oxygen heterocycles from readily available in situ generated pyrylium derivatives has been realized by embracing a multi-coordination approach with helical anion-binding tetrakistriazole catalysts. The high activity of the tetrakistriazole (TetraTri) catalysts, with distinct confined anion-binding pockets, allows for remarkably low catalyst loadings
A facile synthesis of 2-alkyl-substituted chromanones from ortho-acylphenols and terminal alkynoates is described. The method contains two consecutive processes in one-pot reaction through a DABCO-catalyzed condensation reaction and a KOBu'-mediated intramolecular cycloaddition to afford the desired products. (C) 2010 Elsevier Ltd. All Fights reserved.