Assembly of a Benzo-Fused Bridged Ketone Scaffold from 1,5,10-Enediynes through One-Pot Ruthenium-Catalyzed Cyclization/Iodine-Mediated Oxidative Ring Expansion

DFT study on ruthenium-catalyzed N-methylbenzamide-directed 1,4-addition of the ortho C–H bond to maleimide via C–H/C–C activation

B3LYP-D3a+IDSCRF/tzp-dkh(-dfg) calculations indicate that CO as a directing group is much more favourable than the N–H group, and the real active catalyst is an ionic type with one [SbF6]− group.

Nonplanar Tub-Shaped Benzocyclooctatetraenes via Halogen-Radical Ring Opening of Dihydrobiphenylenes

A novel tandem Ru-catalyzed [2+2+2] cycloaddition of arylenynes to dihydrobiphenylenes followed by halogen-radical ring opening has been developed for the construction of tub-shaped halogenated benzocyclooctatetraenes (bCOT’s). Cross-couplings and Diels–Alder reactions of the brominated bCOT’s allow the formation of the corresponding eight-membered ring-fused PAH’s. The halogen-radical ring opening probably occurs via a selective formation of a bis-allyl radical at the 1,3-cyclohexadiene moiety, halogenation at the bridgehead carbon, and finally electrocyclic ring opening.

Small rings in the bigger picture: ring expansion of three- and four-membered rings to access larger all-carbon cyclic systems

The release of the inherent ring strain of cyclobutane and cyclopropane derivatives allows a rapid build-up of molecular complexity. This review highlights the state-of-the-art of the ring expansions of three- and four-membered cycles and is organised by types of reactions with emphasis on the reaction mechanisms. Selected examples are discussed to illustrate the synthetic potential of this elegant synthetic tool.

Copper-Catalyzed Asymmetric Synthesis of Bicyclo[3.n.1]alkenones

A series of highly strained bicyclo[3.n.1]alkenones have been successfully constructed in good-to-excellent enantioselectivities and moderate-to-good yields via copper-catalyzed formal [3+3] cycloaddition. The versatile chiral cycloadducts could be selectively converted into various valuable bridge systems, which hold considerable potential for the construction of natural and bioactive compounds containing a [3.n.1] moiety.

A computational study on ruthenium-catalyzed [4 + 1] annulation via C–H activation: the origin of selectivity and the role of the internal oxidizing group

Internal alkynes with β-H and hydroxyl groups lead to the [4 + 1] annulation.