Synthetic route towards 1,2,3,4-tetrahydroquinoxaline/piperidine combined tricyclic ring system

Abstract

The synthetic route toward novel tricyclic, nitrogen-containing system is\n disclosed. Three novel compounds possessing structural features of\n 1,2,3,4-tetrahydroquinoxaline and decahydropyrido[3,4-b]pyrazine are\n synthesized starting from readily available precursors in six or seven\n steps, of which the last three or four steps respectfully are\n diastereoselective. Key reaction steps include N-acylation, Hofmann\n rearrangement and ring-closing Buchwald-Hartwig reaction. Compounds trans-8,\n cis-12 and trans-12 are synthesized in order to prove that this novel,\n tricyclic system can be functionalized with various groups. Synthetic\n significance of this heterocyclic system lies in the possibility for the\n orthogonal functionalization of three different amino groups, allowing fine\n structural tuning.