Novel routes to 1,2,3,4-tetrahydropyrrolo[1,2-α]pyrazines and 5,6,9,10,11,11a-hexahydro-8H-pyrido[1,2-α]pyrrolo[2,1-c]pyrazines

Condensation reactions of benzotriazole and 2-(pyrrol-1-yl)-1-ethylamine (1) with formaldehyde and glutaric dialdehyde, respectively, afforded intermediates 2 and 6. Subsequent nucleophilic substitutions of the benzotriazole group in 2 and 6 with Grignard reagents, sodium cyanide, and sodium borohydride gave 1,2,3,4-tetrahydropyrrolo[1,2-alpha]pyrazines 3a-e, 4, 5 and 5,6,9,10,11,11a-hexahydro-8H-pyrido[1,2-alpha]pyrrolo[2,1-c]pyrazines 7a-c, 8, 9, respectively, in good yields.