Influence of Lewis acids on the facial selectivity in cycloadditions of sugar-derived dihydropyranones

The influence of such Lewis acids as Et2O·BF3, ZnCl2, SnCl4 and TiCl4 on the stereochemical course of the Diels-Alder cycloadditions of sugar-derived (2S)-alkoxydihydropyranones was studied. The first two catalysts promoted the addition of dienes to give (3S,4aR,8aS)-3-alkoxy-4a,5,8,8a-tetrahydro-2-...

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Autores principales:	Iriarte Capaccio, C.A., Varela, O.
Formato:	JOUR
Materias:	alkadiene carbohydrate derivative chelate Lewis acid pyran derivative tin derivative titanium derivative zinc derivative article catalyst chemical reaction concentration (parameters) cycloaddition Diels Alder reaction proton nuclear magnetic resonance stereochemistry Betulaceae
Acceso en línea:	http://hdl.handle.net/20.500.12110/paper_00404039_v44_n21_p4023_IriarteCapaccio
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	todo:paper_00404039_v44_n21_p4023_IriarteCapaccio
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spelling	todo:paper_00404039_v44_n21_p4023_IriarteCapaccio2023-10-03T14:50:54Z Influence of Lewis acids on the facial selectivity in cycloadditions of sugar-derived dihydropyranones Iriarte Capaccio, C.A. Varela, O. alkadiene carbohydrate derivative chelate Lewis acid pyran derivative tin derivative titanium derivative zinc derivative article catalyst chemical reaction concentration (parameters) cycloaddition Diels Alder reaction proton nuclear magnetic resonance stereochemistry Betulaceae The influence of such Lewis acids as Et2O·BF3, ZnCl2, SnCl4 and TiCl4 on the stereochemical course of the Diels-Alder cycloadditions of sugar-derived (2S)-alkoxydihydropyranones was studied. The first two catalysts promoted the addition of dienes to give (3S,4aR,8aS)-3-alkoxy-4a,5,8,8a-tetrahydro-2-benzopyran-4-ones, and their concentration had almost no effect on the stereochemistry of the reaction. In contrast, the concentration of SnCl4 and TiCl4 had a remarkable influence on the selectivity, and even facial stereoselection reversal has been observed. These results may be ascribed to chelate complexation of the Lewis acid with the carbonyl and the vicinal alkoxy group of the dihydropyranone. © 2003 Elsevier Science Ltd. All rights reserved. Fil:Iriarte Capaccio, C.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Varela, O. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00404039_v44_n21_p4023_IriarteCapaccio
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	alkadiene carbohydrate derivative chelate Lewis acid pyran derivative tin derivative titanium derivative zinc derivative article catalyst chemical reaction concentration (parameters) cycloaddition Diels Alder reaction proton nuclear magnetic resonance stereochemistry Betulaceae
spellingShingle	alkadiene carbohydrate derivative chelate Lewis acid pyran derivative tin derivative titanium derivative zinc derivative article catalyst chemical reaction concentration (parameters) cycloaddition Diels Alder reaction proton nuclear magnetic resonance stereochemistry Betulaceae Iriarte Capaccio, C.A. Varela, O. Influence of Lewis acids on the facial selectivity in cycloadditions of sugar-derived dihydropyranones
topic_facet	alkadiene carbohydrate derivative chelate Lewis acid pyran derivative tin derivative titanium derivative zinc derivative article catalyst chemical reaction concentration (parameters) cycloaddition Diels Alder reaction proton nuclear magnetic resonance stereochemistry Betulaceae
description	The influence of such Lewis acids as Et2O·BF3, ZnCl2, SnCl4 and TiCl4 on the stereochemical course of the Diels-Alder cycloadditions of sugar-derived (2S)-alkoxydihydropyranones was studied. The first two catalysts promoted the addition of dienes to give (3S,4aR,8aS)-3-alkoxy-4a,5,8,8a-tetrahydro-2-benzopyran-4-ones, and their concentration had almost no effect on the stereochemistry of the reaction. In contrast, the concentration of SnCl4 and TiCl4 had a remarkable influence on the selectivity, and even facial stereoselection reversal has been observed. These results may be ascribed to chelate complexation of the Lewis acid with the carbonyl and the vicinal alkoxy group of the dihydropyranone. © 2003 Elsevier Science Ltd. All rights reserved.
format	JOUR
author	Iriarte Capaccio, C.A. Varela, O.
author_facet	Iriarte Capaccio, C.A. Varela, O.
author_sort	Iriarte Capaccio, C.A.
title	Influence of Lewis acids on the facial selectivity in cycloadditions of sugar-derived dihydropyranones
title_short	Influence of Lewis acids on the facial selectivity in cycloadditions of sugar-derived dihydropyranones
title_full	Influence of Lewis acids on the facial selectivity in cycloadditions of sugar-derived dihydropyranones
title_fullStr	Influence of Lewis acids on the facial selectivity in cycloadditions of sugar-derived dihydropyranones
title_full_unstemmed	Influence of Lewis acids on the facial selectivity in cycloadditions of sugar-derived dihydropyranones
title_sort	influence of lewis acids on the facial selectivity in cycloadditions of sugar-derived dihydropyranones
url	http://hdl.handle.net/20.500.12110/paper_00404039_v44_n21_p4023_IriarteCapaccio
work_keys_str_mv	AT iriartecapaccioca influenceoflewisacidsonthefacialselectivityincycloadditionsofsugarderiveddihydropyranones AT varelao influenceoflewisacidsonthefacialselectivityincycloadditionsofsugarderiveddihydropyranones
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Influence of Lewis acids on the facial selectivity in cycloadditions of sugar-derived dihydropyranones

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