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A photocatalyst-free visible-light-induced selenofunctionalization of alkenes has been developed using a variety of nucleophiles. The homolytic scission of diselenides under visible-light conditions coupled with the aerobic selenol oxidation to diselenides allowed the successful implementation of three-component selenofunctionalization under visible-light irradiation in open-air conditions. The mechanistic studies revealed the critical role of oxygen content in a reaction medium, where the electron transfer process from the carbon-based radicals to either molecular oxygen or selenyl radicals was controlled.

A biomimetic alcohol dehydrogenase (ADH)-like oxidation protocol was developed using an

The generation of aminium radical cation species from N-nitrosoamines is disclosed for the first time through visible-light excitation at 453 nm. The developed visible-light-promoted photoaddition reaction of N-nitrosoamines to alkenes was combined with the o-NQ-catalyzed aerobic oxidation protocol of amines to telescope the direct handling of harmful N-nitroso compounds, where the desired α-amino oxime derivatives were obtained in a one-pot tandem N-nitrosation and photoaddition sequence.

A direct cross-coupling between sodium sulfinates and 2H-indazoles has been developed under electrochemical conditions. The utilization of a graphite anode and platinum cathode in an undivided cell with a constant current of 7 mA allowed the concurrent oxidations of sulfinates and 2H-indazoles to sulfonyl radical and radical cationic 2H-indazoles, facilitating the direct radical-radical coupling strategy to 3-sulfonylated 2H-indazole derivatives. The transition-metal- and redox-reagent-free synthetic approach should serve as a valuable synthetic tool to achieve heteroaromatic compounds.

The photoredox chloroacylation of alkenes has been developed as a substitute for the Friedel-Crafts acylation of alkenes to β-chloroketones. The direct generation of acyl radical species from acid chlorides under the photoredox conditions allows the formation of β-chloroketones without dehydrochlorination with the help of KHCO3. The synthetic utility of the current method is demonstrated in the one-pot synthesis of dihydroisoxazole, dihydropyrazole, and dihydropyrimidine-2-thione in 1 mmol scale.

A catalytic asymmetric desymmetrization of cyclohexadienones was accomplished via Van Leusen pyrrole synthesis in the presence of a chiral silver catalyst. The ready access to chiral-fused pyrrole derivatives is attributed to the identification of a suitable isocyanomethyl sulfone surrogate, NasMIC. The current Ag(I)-chiral phosphino-carboamide ligand system can be extended to the kinetic resolution of racemic cyclohexadienones, capitalizing on the differentiated reactivity of chiral quaternary complexes from AgSbF

Two distinctive transition-metal-promoted aerobic oxidation protocols have been developed for the synthesis of isoquinolones from 2-vinylbenzaldehydes and aniline derivatives. Thus, the one-pot tandem reaction sequence of imine formation, thermal 6π-electrocyclization, followed by either Cu(OAc)2-mediated or Pd(OAc)2-catalyzed aerobic oxidation protocol allowed the ready access to isoquinolone derivatives. The control experiments revealed that the 1,2-dihydroisoquinoline intermediates from the 6π-electrocyclization of 1-azatrienes were aerobically oxidized to isoquinolones in the presence of either Cu(OAc)2 or Pd(OAc)2 catalyst.

The synthesis of isoxazoles has been achieved in a continuous flow system composed of two reaction units: the Friedel-Crafts acylation of alkynes and the azide conjugate addition to the resulting β-chlorovinyl ketones followed by a photochemical-thermal reaction sequence. The salient feature of the current flow system includes the safe handling of potentially explosive organic azide species as well as the rapid conversion of batch reactions into flow conditions with the integration of multiple reactor units.

A convenient visible-light photoredox catalysis has been developed for the synthesis of thioesters from two readily available starting materials: acid chlorides and sodium sulfinates. The facile generation of acyl radical species under the visible light photoredox conditions allows the formation of thiyl radical species from sodium sulfinates via multiple single electron transfer reactions, where the final acyl radical-thiyl radical coupling has been accomplished. The direct radical-radical coupling strategy offers a mild and controlled photochemical approach to important synthetic building blocks such as thioesters.

The generation of aminium radical cation species from

A direct cross-coupling between sodium sulfinates and 2

A rhodium-catalyzed decarbonylative aerobic oxidation of cyclic α-diketones has been developed for the first time, where the regioselective formations of α-pyrones and isocoumarins have been achieved. The current decarbonylative aerobic oxidation pathway proceeds via the C-C bond cleavage followed by a C-O bond formation, representing a biomimetic oxidation approach to unsaturated six-membered cyclic lactones. The unique ability of rhodium catalysts to induce the decarbonylative aerobic oxidation opens up a new synthetic toolbox that utilizes the "regioselective single carbon" extrusion strategy.

A palladium-catalyzed intermolecular hydroamination of vinylarene derivatives using anilines has been developed for the first time under aerobic conditions, where the regioselective formation of N-arylketimines is accomplished. The current aerobic oxidative hydroamination pathway of anilines is distinct from that of palladium-catalyzed hydroamination reactions that proceed to give sec-arylethylamine and arylethylamine derivatives, identifying a longstanding missing reaction pathway, Wacker-type amination, to N-arylketimines using anilines. The ready availability of both starting materials, vinylarenes and anilines, offers an attractive and facile synthetic route to N-arylketimines in good to excellent yields.

A tandem aerobic oxidation protocol has been developed for the facile synthesis of indole-3-carboxylates. Two readily available starting materials, anilines and benzylamines, were efficiently cross-coupled under the o-naphthoquinone-catalyzed aerobic oxidation conditions to the corresponding 2-arylmethyleneaminophenylacetates that in turn smoothly underwent the Cu(II)-catalyzed intramolecular Mannich reaction. The resulting indoline derivatives were aerobically oxidized to indole-3-carboxylates, providing a ready access to indole derivatives from two simple amine derivatives.

A tandem three-component reaction has been developed for the synthesis of spirocyclic 2-indolinylformamidines through a cooperative action of palladium and copper catalysts. The Pd-catalyzed benzylation of α-isocyano lactams with 2-bromobenzyl bromides allows efficient formation of α-substituted α-isocyano lactams. A subsequent in situ Cu-catalyzed amine addition to the isocyanide moiety provides amidine intermediates that readily undergo intramolecular N-arylation via the cooperative action of Pd/Cu catalysis, allowing a facile chiral resolution of the spirocyclic 2-indolines.

A tandem synthetic route to a diverse array of cyclic compounds has been developed from Friedel-Crafts acylation of alkynes followed by the microwave irradiation of β-chlorovinyl ketone intermediates. The stereoisomeric β-chlorovinyl ketone intermediates smoothly underwent a thermal α-vinyl enolization and ring expansion to vinyl and carbocyclic furans as well as cyclopetene derivatives in good to excellent yields without the need for any catalysts.

A modular aerobic oxidation of amines to imines has been achieved using an ortho-naphthoquinone (o-NQ) catalyst. The cooperative catalyst system of o-NQ and Cu(OAc)2 enabled the formation of homocoupled imines from benzylamines, while the presence of TFA helped the formation of cross-coupled imines in excellent yields. The current mild aerobic oxidation protocol could also be applied to the oxidation of secondary amines to imines or ketimines with the help of cocatalyst, Ag2CO3, with excellent yields.

A facile approach to spirocyclic pyrrolidinonylformimidamides has been developed via three-component reactions of isocyanides, alkenes, and amines. The reaction proceeds through a sequence of two distinct reaction pathways; the base-catalyzed conjugate addition of α-isocyano lactams to electron-deficient alkenes and the Ag(I)-catalyzed amine insertion to the isocyanide moiety. Both reactions display markedly different reaction kinetics, allowing the one-pot three-component reactions to be performed in the presence of respective catalysts, a Bronsted base and a silver salt. The formation of spirocyclic pyrrolidin-2-ones represents an unusual use of α-isocyano lactam as a two-atom unit in a formal [3 + 2] cycloaddition reaction. The successful identification of ways to defy the typical three-atom unit role of α-isocyano carbonyl compounds in the [3 + 2] cycloaddition pathways manifests a rapid assembly of medicinally important spirocyclic scaffolds from readily available starting materials.

A direct acyl radical addition to 2 H-indazoles has been achieved for the first time, where the less-aromatic quinonoid 2 H-indazoles readily accepted radical species to the C-3 position. Motivated by the lack of direct acylation strategy for 2 H-indazoles, the current method utilizes the radical acceptability of 2 H-indazoles, discovering an ambient temperature reaction to provide facile access to a diverse array of 3-acyl-2 H-indazoles with three points of structural diversification in 25%-83% yields.

A highly selective and practical asymmetric Ag(I) catalyst system has been developed for the [3 + 2] cycloaddition reactions between isocyanoacetates and cyclopentenediones. The current Ag(I) catalyst system tolerates moisture and air and readily utilizes class III solvents such as EtOAc and acetone. The development of on demand generation of an active chiral catalyst in the presence of isocyanides paves a way to the efficient asymmetric preparation of bicyclic pyrrolidines with four stereogenic centers, including two quaternary centers in 80–97% ee.

The direct conjugate addition reactions of imino esters to β-chlorovinyl ketones have been accomplished in the presence of a substoichiometric amount of hard base, LiHMDS. An in situ generated species from the conjugate addition reaction readily acted as autocatalyst to convert the imino esters to its corresponding enolates. By utilizing a sequence of conjugate addition/elimination/lactonization followed by either reduction or reaction with amines, the novel one-pot syntheses of highly functionalized pyranone and pyrrole derivatives were accomplished in good to excellent yields.

A mechanism-driven enantiodivergent approach to chiral 1,1′-bi-2-naphthols via catalytic asymmetric oxidative coupling of 2-naphthol derivatives is described for the first time. By utilizing 2-naphthol derivatives with low oxidation potential, the substrates were activated by either chiral mononuclear or dinuclear vanadium(V) catalyst to promote distinctively different asymmetric reaction pathways: single versus dual substrate activation mechanisms.

The facile synthesis of 6- to 8-membered pyrrololactams has been developed using a ring expansion of spiro-2H-pyrroles, the products of intermolecular alkyne–isocyanide click reactions. The key to successful ring expansion of spiro-2H-pyrroles to pyrrololactams is the enforced orbital overlap between the internal alkene and the amide carbonyl group through the conformationally locked bicyclic structures. The newly disclosed α-isocyano lactams, substrates for click reactions, should find their utility in the synthesis of pharmaceutically important heterocyclic compounds.

A facile synthetic method to chromenones and thiochromenones has been developed using a one-pot Friedel–Crafts acylation of alkynes with suitably substituted benzoyl chlorides. This unified approach to (thio)chromenones is readily applicable to aryl- and alkylalkynes where the stereochemically well-defined β-chlorovinyl ketone intermediates undergo distinctively different cyclization pathways. The ready availability of both starting materials, alkynes and benzoyl chlorides, coupled with the experimental simplicity makes the current synthetic method to (thio)chromenones fast, efficient, and practical.

A one-pot synthesis of 2-naphthol derivatives is accomplished using a tandem Friedel-Crafts reaction sequence. The developed methodology allows for a concomitant construction of up to three C-C bonds between readily available alkynes and phenylacetyl chloride derivatives by an intermolecular Friedel-Crafts acylation of alkynes followed by an intramolecular Friedel-Crafts alkylation of β-chlorovinyl ketone intermediates.

Enantio- and diastereodivergent approaches to pyrrolidines are described by using catalyst- and substrate-controlled reaction pathways. A concerted endo-selective [3 + 2]-cycloaddition pathway is developed for the reaction of methyl imino ester, whereas endo-pyrrolidines with an opposite absolute stereochemical outcome are prepared by using the stepwise reaction pathway of tert-butyl imino ester. The development of catalyst- and substrate-controlled stereodivergent approaches highlights the inherent substrate–catalyst interactions in the [3 + 2]-cycloaddition reactions of metalated azomethine ylides.

The soft α-vinyl enolization of (E)-β-chlorovinyl ketones was investigated in the presence of various halogen electrophiles. Depending on the nature of halogen electrophiles, the selective formation of three products, namely α,α-dichloropropargyl ketones, α,γ-dihaloallenyl ketones, and 3-halofurans, was observed. The observed regiodivergent nucleophilic pathways of (E)-β-chlorovinyl ketones demonstrate the diversity-oriented synthesis strategy in which the nucleophilic reactivity of (E)-β-chlorovinyl ketones can be selectively modulated by the choice of suitable hard and soft electrophiles.

A biotin core has been assembled in a short and efficient sequence utilizing a tandem intramolecular Michael reaction/fragmentation/Michael reaction from vinyl sulfoxide and sulfone alcohols (12 and 13).

[reaction: see text] Addition of diverse nucleophiles to the unsaturated lactone 2 that results from hetero Diels-Alder reaction of Brassard's diene 1 with aldehydes leads to an efficient and general approach to the synthesis of 2,3-dihydro-4H-pyran-4-ones 3.

The cooperative catalyst activity between a chiral transition-metal catalyst and an achiral organocatalyst has been identified as one of the critical asymmetric reaction optimization components in the highly diastereo- and enantioselective aldol reaction of methyl α-isocyanoacetate.

A new approach to both enantioenriched Henry products is developed by use of different molecularities of metal−ligand complexes generated from Cu(I) and Zn(II) metals with readily available chiral amino alcohol 1.