Advances in [4+3]‐Annulation/Cycloaddition Reactions Leading to Homo‐ and Heterocycles with Seven‐Membered Rings

Abstract

In this review, we summarize advances in [4+3] and a few other annulation/cycloaddition reactions for the construction of seven membered rings, with an emphasis on the literature subsequent to the year 2010. The type of products include the following: azepines, diazepines, benzazepinones, 1,2‐diazepinones, oxazepinones, benzothiazepines, benzodiazepinones, benzoxopinones, cyclohepta[b]indoles, benzoxazepines, azepino‐indoles, oxepines/oxazepanes, triazepines oxepinoindolones/azepinoindolones, oxadiazepines, azabicyclooctanes. Emphasis is also given to cover diverse types of annulations; possible intermediates are displayed in the illustrated schemes to aid future work.

Asymmetric [4 + 3] Annulations for Constructing Divergent Oxepane Frameworks via Cooperative Tertiary Amine/Transition Metal Catalysis

“…Over the past years, [4 + 3] and [5 + 2] annulation reactions emerged as powerful strategies for constructing oxepane derivatives including N -heterocyclic carbene (NHC)-activated homoenolates, Lewis base tethered dipoles, Pd-trimethylenemethane intermediates, and 2-indolylmethanols, , furnishing a broad range of aromatic ring fused oxepane derivatives (Scheme a).…”

Recent Advances in Transition-Metal-Free (4+3)-Annulations

“…and carbocycles in 2020. 6 Consequently, our review will cover examples involving acyclic 4-atom equivalents in literature in recent years (2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019)(2020). Following our previous discussion of transition-metal-catalyzed (4+3)-annulations, we will now discuss (4+3)-annulations involving bases, N-heterocyclic carbenes (NHCs), phosphines, Lewis acids, Brønsted acids, and those involving dual-activation modes.…”

Silver‐Catalyzed One‐Pot Access to Diastereoselective Benzo[5,6]oxepino[2,3‐c]pyrroles via Formal (5+2)‐Annulation of Donor‐/Acceptor‐Type Aryl Vinyl Diazosuccinimide with Ketones

“…However, the stereoselective synthesis of either of these scaffolds is quite challenging and it typically needs an elegant ligand‐controlled strategy (Scheme 1B) [7] . Very recently, Schneider and co‐workers [8a] reported a protocol for the construction of bicyclic framework: oxa‐bridged dibenzooxacines (5‐8 fused rings) via formal (4+3)‐cycloaddition [8b–e] involving carbonyl ylide as reactive intermediate. Besides, the reaction of vinyl diazo compounds with aldehydes usually known to form a mixture of oxiranes [ via (2+1)‐cycloaddition] and dihydrofurans [ via formal (3+2)‐cycloaddition] through carbonyl ylide involving metal carbene intermediates (Scheme 1C) [9] .…”