One-step and Solvent-free synthesis of terpene-fused pyrazines

Abstract

Solvent-free condensation reactions were carried out by heating terpene-monooximes with an excess of amines. Employing camphor-and nopinone-derived monooximes, two classes of terpene-fused pyrazine derivatives were synthesized. Besides being solvent-free, the described one-step procedure can be directed towards terpene-fused imidazole or pyrazine derivatives. Whereas the reaction worked well with arylmethanamines bearing a (hetero)aromatic substituent at the α-carbon, alkylamines afforded only imino-oximes. A possible reaction path is presented.