A novel synthesis of hexahydroazoninoindoles using activated alkynes in an azepine ring expansion

Synthesis of Benzoazocines from Substituted Tetrahydroisoquinolines and Activated Alkynes in a Tetrahydropyridine Ring Expansion

“…[11] Recently, we have reported a novel method for the synthesis of tetrahydropyrrolo [2,3-d]azocines, [12] tetrahydroazocino [4,5-b]-and - [5,4-b]indoles, [13] and hexahydroazonino [5,6-b]indoles. [14] It is based on the enlargement of either the tetrahydropyridine or hexahydroazepine fragments in tetrahydropyrrolo [3,2-c]pyridines, tetrahydro-β-and -γ-carbolines, or tetrahydroazepino [3,4-b]-and - [4,3-b]indoles in the presence of activated alkynes. These reactions proceed via the intermediate zwitterion A (Scheme 1), resulting from the Michael addition of the tertiary nitrogen atom to the activated alkynes.…”

Synthesis of hexahydroazonino[5,6-b]indoles from hexahydroazepino[4,3-b]-and-[3,4-b]indoles and activated alkynes

“…4, 5 Recently, a possibility for the synthesis by this method of derivatives of a new heterocyclic sys tem, viz., hexahydroazonino [5,6 b]indoles isomeric in the position of the double bond in the azonine ring, was shown on a model reaction of hexahydroazepino [4,3 b] and [3,4 b]indoles with methyl propiolate. 6 In the present communication, some characteristics of the reaction of hexahydroazepino [4,3 b] and [3,4 b]indoles with me thyl propiolate, acetyl and tosylacetylenes, as well as with dimethyl acetylenedicarboxylate (DMAD), are con sidered. Hexahydroazepino [4,3 b]indoles 1-5 were prepared from 1 oxotetrahydrocarbazoles according to the proce dure described earlier.…”

Interaction of 4-hydroxymethyl- 2-(3,4-dimethoxybenzyl)isoindoline with methyl propiolate

“…In this way tetrahydropyrroloazocines and hexahydroazoninoindoles or substituted pyrroles and indoles [1,2] respectively are formed. This reaction is an efficient method of synthesizing condensed azocines and azonines.…”