Synthesis and molecular structure of 2,3,4,5-tetrahydro-1H-3-benzazepine derivatives and dimethyl 4-cyano-2,3,6,7-tetrahydro-1H-3-benzazonine-5,6-dicarboxylate

Synthesis and X-ray Structural Studies of a Substituted 2,3,4,5-Tetrahydro-1H-3-benzazonine and a 1,2,3,5-Tetrahydro-4,3-benzoxazonine

“…These rearrangements involve three-atom ring expansions with incorporation of an O-C-C (Meisenheimer) or C-C-C (Stevens) unit into the six-membered N-containing ring. Soldatenkov et al have also reported that a tetrahydroisoquinoline N-ylide can undergo a somewhat related [1,4] sigmatropic rearrangement on reaction with dimethyl acetylenedicarboxylate affording a 3-benzazonine derivative in good yield [22]. The results of our work and the single crystal X-ray structural analyses of the benzo-fused nine-membered ring heterocycles produced are discussed in this paper.…”

Ring Expansion of 1,2,3,4-Tetrahydroisoquinolines to Dibenzo[c,f]azonines. An Unexpected [1,4]-Sigmatropic Rearrangement of Nitrile-Stabilized Ammonium Ylides

“…Related methodologies have been described using ester derivatives instead of nitriles . Soldatova and co-workers explored α-amino­nitrile-derived starting materials for the ring expansion of 1-benzyl-1,2,­3,4-tetra­hydro­iso­quino­lines but reported only moderate yields . We anticipated a better outcome if the negative charge in the ammonium ylide is stabilized by an adjacent aryl group.…”

Heterocycles from α‐Aminonitriles

“…[64] Starting from similar tetrahydroiso- www.chemeurj.org 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim quinolinium salts 121 in combination with dimethyl acetylenedicarboxylate, the same authors achieved a ring enlargement by three carbon atoms under formation of 2,3,6,7-tetrahydro-1H-benz[d]azonines 124 (Scheme 25). [64] Starting from similar tetrahydroiso- www.chemeurj.org 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim quinolinium salts 121 in combination with dimethyl acetylenedicarboxylate, the same authors achieved a ring enlargement by three carbon atoms under formation of 2,3,6,7-tetrahydro-1H-benz[d]azonines 124 (Scheme 25).…”

“…Soldatova and co-workers employed the same sequence for the ring homologation of tetrahydroisoquinolinium salts to tetrahydro-3-benzazepines. [64] Starting from similar tetrahydroiso- quinolinium salts 121 in combination with dimethyl acetylenedicarboxylate, the same authors achieved a ring enlargement by three carbon atoms under formation of 2,3,6,7-tetrahydro-1H-benz[d]azonines 124 (Scheme 25). [65] More recently, Lahm et al reported a concise synthesis of polycyclic alkaloids based on the Stevens rearrangement of nitrile-stabilized ammonium ylides derived from spirocyclic ammonium salts.…”

“…Soldatova and co‐workers employed the same sequence for the ring homologation of tetrahydroisoquinolinium salts to tetrahydro‐3‐benzazepines 64. Starting from similar tetrahydroisoquinolinium salts 121 in combination with dimethyl acetylenedicarboxylate, the same authors achieved a ring enlargement by three carbon atoms under formation of 2,3,6,7‐tetrahydro‐1 H ‐benz[ d ]azonines 124 (Scheme ) 65…”