Pyrazines. 2ème communication [1]. II. Synthèse de dihydro‐6,7‐5H‐cyclopenta[b]pyrazines alkylées

Alkyl‐5 H ‐6,7‐dihydrocyclopenta[ b ]pyrazines are prepared by condensation of cyclopentenolones with alkylenediamines or of aliphatic α‐diketones with 1,2‐diaminocyclo pentanes. Products so obtained were dehydrogenated using palladium on activated charcoal, or copper chromite. NMR. and mass spectra are given for 21 bicyclic pyrazines and intermediates, and their IR. spectra are compared.