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

Jean-Martial L'Helgoual'Ch (1) , Ghenia Bentabed-Ababsa (2) , Floris Chevallier (1) , Aïcha Derdour (2) , Florence Mongin (1)

1 CPM - Chimie et Photonique Moléculaires
2 Laboratoire de Synthèse Organique Appliquée

The deproto-metalation reactions of pyrimidine and pyrazine were regioselectively carried out using lithium tri(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 iodopyrazine in 71 and 63% yields, respectively. The same reaction performed on pyri-dazine afforded a mixture of the 3- and 4-iodo derivatives (55 and 41% yields, respectively). From pyrazine, the 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 1/3).

Mots clés: Metalations; Cadmium; Lithium; Heterocycles; Iodine

Domaines: Chimie organique

Jean-Martial L'Helgoual'Ch, Ghenia Bentabed-Ababsa, Floris Chevallier, Aïcha Derdour, Florence Mongin. Synthesis of 2,5-Diiodopyrazine by Deprotonative Dimetalation of Pyrazine. Synthesis: Journal of Synthetic Organic Chemistry, 2008, 24, pp.4033-4035. ⟨10.1055/s-0028-1083218⟩. ⟨hal-01010345⟩