Synthesis 2008(24): 4033-4035  
DOI: 10.1055/s-0028-1083218
PSP
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of 2,5-Diiodopyrazine by Deprotonative Dimetalation of Pyrazine

Jean-Martial L’Helgoual’cha, Ghenia Bentabed-Ababsaa,b, Floris Chevalliera, Aïcha Derdourb, Florence Mongin*a
a Chimie et Photonique Moléculaires, UMR 6510 CNRS, Université de Rennes 1, Bâtiment 10A, Case 1003, Campus Scientifique de Beaulieu, 35042 Rennes, France
Fax: +33(223)236955; e-Mail: florence.mongin@univ-rennes1.fr;
b Laboratoire de Synthèse Organique Appliquée, Faculté des Sciences de l’Université, Université d’Oran Es-Senia, BP 1524 Es-Senia, Oran 31000, Algeria
Further Information

Publication History

Received 29 July 2008
Publication Date:
06 November 2008 (online)

Abstract

The deproto-metalation reactions of pyrimidine and pyrazine were regioselectively carried out using lithium tris(2,2,6,6-tetra­methylpiperidino)cadmate in tetrahydrofuran at room temperature. This result was demonstrated by subsequent trapping with iodine to afford­ 4-iodopyrimidine and 2-iodopyrazine in 71% and 63% yields, respectively. The same reaction performed on pyridazine afforded a mixture of the 3- and 4-iodo derivatives (55% and 41% yields, respectively). From pyrazine, access to the 2,5-diiodo derivative (40% on a 25 mmol scale) proved possible using a larger amount of base (1 equiv instead of 0.33).

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L’Helgoual’ch, J.-M.; Bentabed-Ababsa, G.; Chevallier, F.; Yonehara, M.; Uchiyama, M.; Derdour, A.; Mongin F.; Chem. Commun.; 2008, in press.