Enantioselective Palladium(II)-Catalyzed Desymmetrizative Coupling of 7-Azabenzonorbornadienes with Alkynylanilines

A PdII -catalyzed, domino enantioselective desymmetrizative coupling of 7-azabenzonorbornadienes with alkynylanilines is disclosed herein. This operationally simple transformation generates three covalent bonds and two contiguous stereocenters with excellent enantio- and diastereo-selectivity. The resulting functionalized indole-dihydronaphthalene-amine conjugates served as an appealing platform to streamline the diversity-oriented synthesis (DOS) of other valuable enantioenriched compounds. DFT calculations revealed that the two stabilizing non-covalent interactions contributed to the observed enantioselectivity.

Ruthenium(II)-Catalyzed S(II)-Directed Aromatic C-H Allylation with Vinylaziridines

The ruthenium-catalyzed reaction of aryl methyl thioethers with vinylaziridines affords ortho-position mono- or bis-allylation products depending on substituents on the phenyl rings of sulfide substrates or the ratio of reactants. The reaction also features mild reaction conditions, good product yields, wide scope of substrates, good compatibility of functional groups, and the selective formation of E-configurated C-C double bonds.

Three-Component 1,2-Carboamidation of Bridged Bicyclic Alkenes via RhIII-Catalyzed Addition of C-H Bonds and Amidating Reagents

A three-component method is described for the preparation of syn-1,2-disubstituted bridged bicyclic compounds. The reaction was demonstrated for readily available aromatic and heteroaromatic C-H bond substrates with tertiary and secondary amide, lactam, pyrazole, and triazole directing groups and a variety of bridged bicyclic alkenes, including norbornene, benzonorbornadiene, oxygen- and nitrogen-bridged analogs, and an unsaturated tropinone. A broad dioxazolone scope was also observed. The use of a chiral Cp-derived RhIII catalyst enables asymmetric synthesis of products.

Synthesis of 4-ethenyl quinazolines via rhodium(iii)-catalyzed [5 + 1] annulation reaction of N-arylamidines with cyclopropenones

An unprecedented synthesis of 4-ethenyl quinazolines/2-benzoyl quinazolines via Rh(iii)-catalyzed C–H annulation reaction was reported.

Multicomponent Synthesis of Isoindolinones by RhIII Relay Catalysis: Synthesis of Pagoclone and Pazinaclone from Benzaldehyde

A practical one-pot isoindolinone synthesis enabled by Rh^III catalysis was developed. The advantage of this protocol is that it does not require pre-preparation of amide substrates, because Rh^III participates in two reactions independently. This mild, operationally multicomponent process transforms a wide variety of commercially available aldehydes into the corresponding γ-lactams in good yields, thereby demonstrating that N-pyridin-2-yl benzamide is an effective directing group. Notably, the anxiolytic drugs pagoclone and pazinaclone can be directly prepared by this methodology.

An Enantioselective Cpx Rh(III)-Catalyzed C-H Functionalization/Ring-Opening Route to Chiral Cyclopentenylamines

A chiral Cp^x Rh^III catalyst system in situ generated from a Cp^x Rh^I (cod) precatalyst and bis(o-toluoyl) peroxide as activating oxidant was developed for a C-H activation/ring-opening sequence between aryl ketoxime ethers and 2,3-diazabicyclo[2.2.1]hept-5-enes. This transformation provides access to densely functionalized chiral cyclopentenylamines in excellent yields and enantioselectivities of up to 97:3 er. The reported method is also well suitable for asymmetric alkenyl C-H functionalizations of α,β-unsaturated oxime ethers, furnishing skipped dienes with high levels of enantiocontrol.

Trisannulation of benzamides and cyclohexadienone-tethered 1,1-disubstituted allenes initiated by Cp*Rh(iii)-catalyzed C–H activation

A trisannulation of benzamides and cyclohexadienone-tethered 1,1-disubstituted allenes was achieved via the initiation of Cp*Rh(iii)-catalyzed C–H bond activation.

Multicomponent Synthesis of Tetrahydroisoquinolines

A multicomponent synthesis of tetrahydroisoquinolines from carboxylic acids, alkynyl ethers, and dihydroisoquinolines is described. This process features readily available starting materials, simple experimental procedures for achievement of molecule complexity, and structural diversity. The preliminary control experiment and crossover reaction provide important insight into the reaction mechanism. The formed tetrahydroisoquinolines could be transformed to an array of compounds.

Facile synthesis of carbo- and heterocycles via Fe(iii)-catalyzed alkene hydrofunctionalization

A facile synthesis of carbo- and heterocycles via Fe(iii)-catalyzed alkene hydrofunctionalization has been developed.

C–H bond cleavage occurring on a Rh(v) intermediate: a theoretical study of Rh-catalyzed arene azidation

Our theoretical calculations indicated that the oxidation of Rh(iii) to Rh(v) by PhI(OAc)OTs is a facile process. Subsequent electrophilic deprotonation was shown to occur from a Rh(v) intermediate rather than a Rh(iii) intermediate.

Metal-Involving Synthesis and Reactions of Oximes

This review classifies and summarizes the past 10-15 years of advancements in the field of metal-involving (i.e., metal-mediated and metal-catalyzed) reactions of oximes. These reactions are diverse in nature and have been employed for syntheses of oxime-based metal complexes and cage-compounds, oxime functionalizations, and the preparation of new classes of organic species, in particular, a wide variety of heterocyclic systems spanning small 3-membered ring systems to macroheterocycles. This consideration gives a general outlook of reaction routes, mechanisms, and driving forces and underlines the potential of metal-involving conversions of oxime species for application in various fields of chemistry and draws attention to the emerging putative targets.

Rh(III)-catalyzed oxidative ortho-C–H alkylation of 2,4-diarylquinazoline with potassium alkyltrifluoroborates

Alkyltrifluoroborates were used for Rh(III)-catalyzed ortho-alkylation of 2,4-disubstituted quinazoline via C–H bond activation. The reaction proceeded well with a broad substrate scope, providing a direct way to access high functional quinazoline core structure derivatives in yields up to 95%.

Manganese-catalyzed allylation via sequential C-H and C-C/C-Het bond activation

Manganese-catalyzed sequential C-H and C-C/C-Het bond activation to synthesize allylic alcohols, allylated arenes, functionalized cyclopentenes and skipped dienes is reported. This protocol can be readily scaled up and various coupling partners are applied in manganese catalysis for the first time. Moreover, manganese-catalyzed alkenyl C(sp²)-H activation is also shown. Complimentary to the standard solution-based protocols, these reactions also proceed efficiently under neat conditions, which is unprecedented for abundant metal catalyzed C-H activation reactions.

Rhodium(iii)-catalyzed directed C–H benzylation and allylation of indoles with organosilicon reagents

Rhodium(iii)-catalyzed C2-benzylation and allylation of indoles with organosilicon reagents via chelation-assisted C–H activation has been developed.

Pd-Catalyzed oxidative annulation of enamides with diazabicyclic olefins: rapid access to cyclopentene fused 2-pyrrolines

A catalytic tandem transformation via C–H activation of enamides for the stereoselective synthesis of cyclopentene fused 2-pyrrolines has been realized.

Transition metal-catalysed couplings between arenes and strained or reactive rings: combination of C–H activation and ring scission

Transition metal-catalysed systems of C–H activation of arenes in combination with opening of strained or reactive three, four, and five membered rings are summarized in this review.

Rh(iii)-catalyzed C–H activation/cyclization of oximes with alkenes for regioselective synthesis of isoquinolines

A Rh(iii)-catalyzed C–H activation/cyclization of oximes and alkenes for facile and regioselective access to isoquinolines has been developed.