Synthesis of Ring-Fused 1-Benzazepines via [1,5]-Hydride Shift/7-Endo Cyclization Sequences

Abstract

Synthesis of 1-benzazepines has been achieved via a [1,5]-hydride shift/7-endo cyclization sequence. The focus of this research is a direct transformation of 2-(aryl)cyclopropane 1,1-diester derivatives into 1-benzazepines using a cyclopropane moiety as the hydride acceptor in internal redox reactions.

I2‐Promoted Intramolecular Oxidative Cyclization of Butenyl Anilines: A Facile Route to Benzo[b]azepines

“…For instance, Wang [11] developed a method for the construction of benzo[ b ]azepines via copper‐catalyzed oxidative C( sp 3 )−H/C( sp 2 )−H cross‐coupling (Scheme 1a). Kim [12] reported the Lewis acid catalyzed synthesis of ring‐fused 1‐benzazepine derivatives from 2‐(aryl)cyclopropane 1,1‐diesters via [1,5]‐hydride shift/cyclization sequences (Scheme 1b). In 2018, Shi [13] disclosed a Ni‐catalyzed method for the preparation of benzo[ b ]naphtho[1,2‐ d ]azepines via intramolecular cyclization of alkyl bromide‐tethered alkylidenecyclopropanes (Scheme 1c).…”

Donor–Acceptor Cyclopropanes as an Expedient Building Block Towards the Construction of Nitrogen‐Containing Molecules: An Update

“…Kim et al. reported the Lewis acid‐catalyzed [1,5]‐hydride shift and subsequent 7‐ endo cyclization of DAC‐containing cyclic amine 151 to furnish 1‐benzazepines 152 (Scheme a) . In this protocol, the cyclopropane moiety is used as the hydride acceptor in the internal redox reaction.…”

Construction of N‐Heterocycles through Cyclization of Tertiary Amines

“…Kim and co‐workers recently reported that donor–acceptor cyclopropane moieties could act as hydride acceptors (Scheme ) . In the presence of Lewis acid catalysts, tertiary amines 63 bearing a donor–acceptor cyclopropane group could undergo a [1,5]‐hydride transfer process, thus generating a zwitterion intermediate M34 that is available for 7‐ endo cyclization.…”

“…[55] Kim and co-workersr ecently reported that donor-acceptor cyclopropane moieties could act as hydride acceptors (Scheme 27). [56] In the presence of Lewis acid catalysts, tertiary amines 63 bearing ad onor-acceptor cyclopropane group Scheme22. Gold-catalyzed cyclization involving ah ydridet ransfer process.…”