Synthesis 2001(14): 2175-2179
DOI: 10.1055/s-2001-18070
PAPER
© Georg Thieme Verlag Stuttgart · New York

Mild Regioselective Halogenation of Activated Pyridines with N-Bromosuccinimide

Victoria Cañibanoa, Justo F. Rodrígueza, Mercedes Santosa, M. Ascensión Sanz-Tejedor*a, M. Carmen Carreñob, Gema Gonzálezb, José L. García-Ruano*b
Organic Chemistry Department (E.T.S.I.I.), Universidad de Valladolid, Pº del Cauce s/n, 47011-Valladolid, Spain
Fax: +34(983)423310; e-Mail: atejedor@dali.eis.uva.es;
Organic Chemistry Department (C-I), Universidad Autónoma, Cantoblanco, 28049-Madrid, Spain
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Publication History

Received 4 July 2001
Publication Date:
09 August 2004 (online)

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Abstract

Regioselective mono and dihalogenations of amino, hydroxy and methoxy pyridines (2-, 3-, and 4-substituted) as well as 2,6-dimethoxy pyridine with N-bromosuccinimide in different solvents have been studied. Reactivity of the substrates decreases in the order amino>hydroxy>methoxy and regioselectivity depends on the position of the substituent (2-substituted > 3-substituted). In most of the cases we obtained monobrominated derivatives regioselectively and in high yields. Hydroxy and amino pyridines can also be dibrominated in almost quantitative yield with 2 equivalents of NBS.