Synthesis and characterization of pyrimidyl- and pyrazinylselenium compounds: X-ray structure of 2,5-bis(methylselenenyl)pyrazine

• Synthesis of pyrimidyl- and pyrazinylselenium compounds is presented.
• Lithiation of pyrimidine is achieved through its complexation with 2.2 equiv. of BF3·Et2O.
• BF3-complexation does not promote the lithiation of unsubstituted pyrazine ring.

A methodology for the lithiation of pyrimidine (1a) was developed and used for the synthesis of pyrimidylselenium compounds. The procedure involved prior complexation of 1a with 2.2 equiv. of BF3·Et2O followed by a reaction with LDA or LTMP. The pyrazinylselenium derivatives were synthesized from the direct lithiation of pyrazine (1b) as the BF3-directed lithiation failed to give the desired products. All the synthesized compounds were characterized by elemental analysis, NMR (1H and 13C) and Mass spectroscopy. In addition, 2,5-bis(methylselenenyl)pyrazine (9b) was characterized by single crystal X-ray crystallography.

A methodology involving the BF3-directed lithiation of pyrimidine was used for the synthesis of pyrimidylselenium compounds. For pyrazinylselenium derivatives, the direct lithiation of pyrazine with LDA was employed as the BF3-directed lithiation failed to give the desired products.Figure optionsDownload as PowerPoint slide