Lithium Benzocyclobuteneoxide as a Precursor of a Vinylogous Enolate: Solvent‐Controlled Synthesis of Highly Functionalized Seven‐Membered Benzocarbocycles

RhI‐Catalyzed Benzo/[7+1] Cycloaddition of Cyclopropyl‐Benzocyclobutenes and CO by Merging Thermal and Metal‐Catalyzed CC Bond Cleavages

“…Recently Dong and co‐workers2 reported benzocyclobutenones can undergo intramolecular [4+2] and [4+2–1] reactions by selective proximal CC cleavage to give benzene‐fused six‐ and five‐membered rings, respectively, and in these reactions, benzocyclobutenones can be regarded as benzo/4‐C and benzo/3‐C synthons. Other elegant works from Barluenga and Aguilar’s,3a,b Nemoto’s,3c Murakami’s,3d and Wang’s3e groups also provide access to different sized (5‐ to 7‐membered) benzene‐fused rings. However, transition‐metal‐catalyzed cycloadditions of benzocyclobutenes to synthesize benzo/8 skeletons were not available 4.…”

Fischer Carbene Complexes: A Glance at Two Decades of Research on Higher‐Order Cycloaddition Reactions

“…employed benzocyclobutenol 92 and alkynyl carbene complexes 91 to perform a [4+3] cycloaddition, resulting in a mixture of 93 and 94 , both being seven‐membered cyclic compounds. A preference for 94 takes place with THF, and the exclusive formation of 93 with diethyl ether [121] …”

“…This protocol does not deliver the expected [4+2] cycloadduct, but a mixture of benzocycloheptene ketals 93 and benzocycloheptenones 94 instead. The reaction yield can be optimized by employing tungsten complexes (Scheme 16A) [121] . Expanding on the same strategy, [4+3] cycloaddition between o ‐QDMs ( 95 and 97 ) and alkynyl FCCs 91 was evaluated, finding that benzoheptacarbocycles 93 and 94 are provided.…”

Understanding the Reactivity of Group 6 Metal (M = Cr, W) Alkynyl Fischer Carbene Complexes with Multi‐Reactive Masked Dienes

“…These reactions have involved, among others, O, N, or P nucleophiles, [4] N-heterocyclic carbenes, [5] and enolates. [6] Additionally, the M(CO) 5 moiety also renders the carbene carbon highly reactive towards nucleophiles, giving rise to the real possibility of competition between 1,2-and 1,4-addition in these substrates. [2,4] bis-carbene complexes, obtained by a sequential 1,4-C-and 1,4-O-addition process with high diastereoselectivity and only in the presence of an excess of base.…”