Intermolecular and regioselective access to polysubstituted benzo- and dihydrobenzo[c]azepine derivatives: modulating the reactivity of group 6 non-heteroatom-stabilized alkynyl carbene complexes.
We highlight the versatility of non-heteroatom-stabilized tungsten-carbene complexes 3 synthesized in situ, which have been used in a modular approach to access 2-benzazepinium isolable intermediates 5. By employing very mild conditions, benzazepinium derivatives 5 have been obtained in high yield from simple compounds, such as acetylides 2, Fischer-type alkoxycarbenes 1, and phenylimines 4. The process, involving a formal [4+3] heterocycloaddition, occurs in a totally regioselective manner, which differs from the approach previously observed in similar procedures for other carbene analogues. This work, which involves three components, reveals a control of the reactivity of non-heteroatom-stabilized carbene complexes 3 ([4+3] vs. [2+2]-heterocycloaddition reactions) depending on the acetylide substitution pattern. The influence of the substitution pattern in the behavior of the complexes has been computationally analyzed and rationalized. Finally, elaboration of the 2-benzazepinium intermediates allows access to 3H-benzo[c]azepines 6 and 3H-1,2-dihydrobenzo[c]azepines 7-9 with high control of the substitution of the nine positions of the heterocycle.
Departamento de Química Orgánica e Inorgánica e Instituto Universitario de Química Organometálica "Enrique Moles" Unidad Asociada al C.S.I.C. Universidad de Oviedo, C./Julián Clavería, 8, 33006 Oviedo (Spain).
Jairo
J
González
Aránzazu
A
Gómez
Ignacio
I
Funes-Ardoiz
Javier
J
Santamaría
Diego
D
Sampedro
D001552:Benzazepines / Q000737:chemistry*; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry; D061565:Cycloaddition Reaction; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008968:Molecular Conformation; D013237:Stereoisomerism; D014414:Tungsten / Q000737:chemistry
D001552:Benzazepines; D056831:Coordination Complexes; C030011:carbene; D008697:Methane; D014414:Tungsten
alkynes; carbenes; heterocycles; imines; regioselectivity