Azacycloalkanes XXX. Pyrrolo [1,2-a] pyrazines with variable degrees of pyrazine ring saturation and their hypotensive activity

Asymmetric Synthesis of 1-Substituted 1,2,3,4-Tetrahydropyrrolo[1,2-a]pyr­azines

“…1,2,3,4-tetrahydropyrrolo [1,2-a]pyrazines, e.g. 1 (Scheme 1), are extremely useful because of their antiamnesic, antihypoxic, 1 psychotropic, 2 and antihypersensitive 3 activities. 4 Moreover, a stereochemically defined 3,5,5-trisubstituted 2,4-dioxo derivative is a potent inhibitor of aldose reductase.…”

“…5 1-Substituted and 1,2-disubstituted 1,2,3,4-tetrahydropyrrolo[1,2-a]pyrazines 1 have been synthesized by hydrogenation or reduction of 2-substituted 3,4-dihydropyrrolo[1,2-a]pyrazines 2. 1,[6][7][8] The dihydro compounds 2 are, in turn, prepared by reaction of 2-furylcarbaldehyde or 2-furyl ketones with ethylenediamine, [9][10][11] or by addition of Grignard reagents to unsubstituted 2 (R 1 = H). 12 Furthermore, hydrogenation of the pyrrole ring under more-forcing conditions has been used to obtain octahydro derivatives which are useful intermediates for the synthesis of coronary dilators and neuroleptics.…”

“…1,[6][7][8] The dihydro compounds 2 are, in turn, prepared by reaction of 2-furylcarbaldehyde or 2-furyl ketones with ethylenediamine, [9][10][11] or by addition of Grignard reagents to unsubstituted 2 (R 1 = H). 12 Furthermore, hydrogenation of the pyrrole ring under more-forcing conditions has been used to obtain octahydro derivatives which are useful intermediates for the synthesis of coronary dilators and neuroleptics. 8 Dihydro compounds 2 have also been produced by phosphorus oxychloride-mediated condensation of N- [2-(pyrrol-1-yl)ethyl]carboxamides 3, which are obtained, in turn, from 2,5-dimethoxytetrahydrofuran.…”

An Efficient Approach to the Synthesis of Alkyl 7-Hydroxy-1-oxo-1,2,3,4- tetrahydropyrrolo[1,2-a]pyrazine-8-carboxylates via a One-Pot, Three-Component Reaction

“…2 Accordingly, the synthesis of new pyrroles and pyrrolefused heterocyclic derivatives have been considered by chemists, and a range of methods have been reported for their synthesis. 9,10 1,2,3,4-Tetrahydropyrrolo[1,2-a]pyrazine derivatives are one of the most important class of pyrrole-fused heterocycles due to their broad biological activities, including antihypersensitive, 11 antihypoxic, 12 psychotropic, 13 and antiarrhythmic properties. 14 Moreover, they are also reported as serotonin and noradrenaline reuptake inhibitors, 15 aldose reductase inhibitors, 16 and potassium channel ligands.…”

Highly Efficient Access to Original Polycyclic Pyrrolopiperazine Scaffolds by a Three-Component Reaction with 1,3-Dicarbonyls

“…8 Herein we present the direct, high-yielding one-pot conversion of simple 1,3-dicarbonyl compounds 9 1 into pyrrolopiperazine scaffolds 4 promoted by 4 Å molecular sieves (MS). The presence of the 1,2,3,4-tetrahydropyrrolo[1,2-a]pyrazine core 10 is of interest for both biological and synthetic purposes. Compounds with a related structure are found in some families of naturally occurring marine alkaloids which have been the centre of much recent attention.…”