Chemo-, Regio-, and Stereoselective Silver-Catalyzed Aziridination of Dienes: Scope, Mechanistic Studies, and Ring-Opening Reactions
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Departament de Química Analítica i Química Orgànica, Facultat de Química, Universitat Rovira i Virgili, C/Marcel·lí Domingo s/n, 43007 Tarragona,Spain
‡ Laboratorio de Catálisis Homogénea, Unidad Asociada al CSIC, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Química y Ciencia de los Materiales, Universidad de Huelva, Campus de El Carmen 21007 Huelva, Spain
† Institute of Chemical Research of Catalonia, ICIQ, Av. Països Catalans 16, 43007 Tarragona, Spain
§ Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
J. Am. Chem. Soc., Article ASAP
DOI: 10.1021/ja412547r
Publication Date (Web): March 12, 2014
Copyright © 2014 American Chemical Society
perez@dqcm.uhu.es, sergio.castillon@urv.cat, fmaseras@iciq.es, mmdiaz@dqcm.uhu.es, maribel.matheu@urv.cat
Abstract
Silver complexes bearing trispyrazolylborate ligands (Tpx) catalyze the aziridination of 2,4-diene-1-ols in a chemo-, regio-, and stereoselective manner to give vinylaziridines in high yields by means of the metal-mediated transfer of NTs (Ts = p-toluensulfonyl) units from PhI═NTs. The preferential aziridination occurs at the double bond neighboring to the hydroxyl end in ca. 9:1 ratios that assessed a very high degree of regioselectivity. The reaction with the silver-based catalysts proceeds in a stereospecific manner, i.e., the initial configuration of the C═C bond is maintained in the aziridine product (cis or trans). The degree of regioselectivity was explained with the aid of DFT studies, where the directing effect of the OH group of 2,4-diene-1-ols plays a key role. Effective strategies for ring-opening of the new aziridines, deprotection of the Ts group, and subsequent formation of β-amino alcohols have also been developed.
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