Amine‐Substituted Diazocine Derivatives – Synthesis, Structure, and Photophysical Properties

Abstract

Dedicated to Prof. François Diederich on his retirement. Thank you for mentorship and support.A series of amine-substituted diazocines were synthesized in three steps from methyl 2-aminobenzoate or methyl 3-aminonaphtholate. The saddle-shaped diazocine compounds showed similar interplane angle of 75°d espite the different steric bulk of the amine substituents. In electrochemical experiments, these diazocines showed irreversible reduction most likely producing indolo [3,2-b]indoles rather than forming the 10-electron planar aromatic species. The carbazole-substituted naphthodiazocines showed the most interesting photophysical properties with evidence of transition from the saddle-shaped ground state to a planar excited state geometry. Scheme 2. The synthesis of dichlorodibenzo[b,f][1,5]diazocine 5 and dichlorodinaphtho[b,f][1,5]diazocine 8. Scheme 3. The synthesis of amine-substituted dibenzo[b,f][1,5]diazocines 1a -1e. Scheme 4. The synthesis of diphenylamine and carbazole- substituted diazocines 1f, 1g, 2f, and 2g.

Synthetic strategies and diversification of dibenzo[1,5]diazocines

“…28,29 Interestingly, the boat structure of dibenzo [1,5]diazocine is reversible and can be converted to a Hückel dianion with an aromatic planar conformation and with ten π-electrons via a twoelectron reduction process (Scheme 1a). [30][31][32][33] Furthermore, the reductive-ring closure reaction of dichlorodibenzo[b,f] [1,5]diazocine leads to the formation of a diverse range of π-conjugated indolo [2,3-b]indole derivatives (Scheme 1b). 30,[34][35][36] This synthetic protocol is widely utilised for the preparation of materials for organic solar cells 37,38 and organic field-effect transistors (OFETs).…”

“…[30][31][32][33] Furthermore, the reductive-ring closure reaction of dichlorodibenzo[b,f] [1,5]diazocine leads to the formation of a diverse range of π-conjugated indolo [2,3-b]indole derivatives (Scheme 1b). 30,[34][35][36] This synthetic protocol is widely utilised for the preparation of materials for organic solar cells 37,38 and organic field-effect transistors (OFETs). 39 This review summarises the versatile methodologies and functionalisation of substituted dibenzo [1,5]diazocines revealed over the last two decades.…”

“…30–33 Furthermore, the reductive-ring closure reaction of dichlorodibenzo[ b , f ][1,5]diazocine leads to the formation of a diverse range of π-conjugated indolo[2,3- b ]indole derivatives (Scheme 1b). 30,34–36 This synthetic protocol is widely utilised for the preparation of materials for organic solar cells 37,38 and organic field-effect transistors (OFETs). 39…”