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Paper | Regular issue | Vol 87, No. 3, 2013, pp.571-582
Published online, 16th January, 2013
DOI: 10.3987/COM-12-12637
A Convenient Methodology for the in situ Oxidation of 4-Substituted Urazoles. Setting Up a One-Pot Procedure for the Efficient Protection of Dienes

María A. Fernández-Herrera, Jesús Sandoval-Ramírez,* Sara Montiel-Smith, and Socorro Meza-Reyes

*Organic Chemistry, Facultad de Ciencias Químicas, Benemerita Universidad Autonoma de Puebla, Blv 14 Sur y Av. San Claudio CU, 72570, Mexico

Abstract

The oxidation of 4-substituted urazoles to the corresponding 1,2,4-triazoline-3,5-diones can be performed selectively in the presence of dienic systems by the action of the nitrosonium ion, formed in situ by stoichiometric amounts of sodium nitrite and acetic acid. This convenient methodology is mild, fast, and allows the efficient protection of dienic systems in a one-pot procedure. The dienes were not affected whatsoever by the nitrosonium ion, and react extremely fast with triazolinediones; promptly forming the corresponding Diels-Alder cycloadducts in good to excellent yields. The reaction medium did not affect steroids having an extra double bond at the side chain or an acid-labile spiroketal moiety.