NOVEL RING TRANSFORMATIONS OF PYRAZINES BY INTRAMOLECULAR DIELS-ALDER REACTIONS

Article abstract of DOI:10.1016/S0040-4020(88)90036-1

Pyrazines carrying the ω-alkyne side-chain -XCH2CH2<*>CH, (X = O,N,S,SO,SO2,C(CN)2) undergo on heating an intramolecular Diels-Alder reaction.Pyrazines with the electron donating atom (O,N or S) in the side-chain afford -fused pyridines as main products, whereas (3-butynylsulfinyl)pyrazine and (3-butynylsulfonyl)pyrazine are exclusively converted into -fused pyridines.A -fused pyridine is also the major product in the reaction of 2,5-bis(1,1-dicyano-4-pentynyl)pyrazine.