The synthesis of pyrroles and oxazoles based on gold α-imino carbene complexes.

Cationic gold complexes of α-oximimino carbenes have been identified to react with weak nucleophiles including enol ethers and nitriles. These findings allowed us to develop the highly efficient synthesis of pyrroles and oxazoles.

Synthesis of unsymmetrical pyrazines based on α-diazo oxime ethers.

Synthesis of unsymmetrically substituted pyrazines has been a challenge. The reactivity of α-imino carbenoids derived from α-diazo oxime ethers has been exploited for pyrazine synthesis, in which the reaction of α-diazo oxime ethers with 2H-azirines provides highly substituted pyrazines in good to excellent yields.

A synthesis of (1E,3E)-TMS dienes from keto-xanthates via Chugaev-type elimination.

An efficient route leading to exclusively (1E,3E)-TMS dienes is described. Radical xanthate addition of keto-xanthates to vinyltrimethylsilane followed by one-pot Chugaev elimination/cyclization and in situ oxidation with m-CPBA afforded the corresponding TMS 2-sulfolenes. Isomerization to 3-sulfolenes by the action of DBU with the extrusion of sulfur dioxide in refluxing toluene gave the titled (1E,3E)-TMS dienes.

Palladium(II)-catalyzed ortho-arylation of benzylic phosphonic monoesters using potassium aryltrifluoroborates.

The new monophosphonic acid directing group was successfully utilized in the Pd (II)-catalyzed ortho-arylation of benzylic phosphonic monoesters using potassium aryltrifluoroborates. A wide range of benzylic phosphonic monoesters underwent clean ortho-arylation in high yields, and excellent functional group tolerance was also observed.

Rhodium(iii)-catalyzed ortho-olefination of aryl phosphonates.

Rhodium(iii)-catalyzed C-H olefination of aryl phosphonic esters is reported for the first time. In this mild and efficient process, the phosphonic ester group is utilized successfully as a new directing group. In addition, mono-olefination for aryl phosphonates is observed using a phosphonic diamide directing group.

Free-radical variant for the synthesis of functionalized 1,5-diketones.

A free-radical approach for the synthesis of functionalized 1,5-diketones has been accomplished through an effective combination play between alkenylacylphosphonates and keto-xanthates as radical surrogates of enolates and enones, respectively.

ortho-Acetoxylation of phosphonic and phosphoric monoacids via Pd(II) catalysis.

A simple and efficient method is developed for Pd-catalyzed ortho-acetoxylation using organophosphates, namely, benzylic phosphonic and aryl phosphoric monoacids, as the directing group.

Palladium-catalyzed C-H arylation using phosphoramidate as a directing group at room temperature.

This communication describes the first phosphoramidate directing group for synthetically useful arylation. Remarkably, the nature of a new directing group drives selective C-H bond activation to afford diverse N-aryl phosphoramidates in good to excellent yields at room temperature.

Pd(II)-catalyzed ortho-arylation of aryl phosphates and aryl hydrogen phosphates with diaryliodonium triflates.

Functionalized biaryl compounds were successfully synthesized using phosphates as the ortho-directing group in the Pd(II)/Pd(IV) catalytic cycle.

Palladium-catalyzed ortho-alkenylation of aryl hydrogen phosphates using a new mono-phosphoric acid directing group.

A highly efficient Pd-catalyzed ortho-alkenylation is reported using a mono-phosphoric acid-directing group for the first time. This phosphoric acid-directing group is successfully utilized for the synthesis of various alkenylated products and offers a new approach to transition-metal-catalyzed C-H activation.

Palladium(II)-catalyzed ortho-olefination of benzylic phosphonic monoesters.

The new monophosphonic acid directing group is successfully utilized in the Pd(II)-catalyzed ortho-olefination of benzylic phosphonic monoesters and offers further development of other phosphoryl-related directing groups in the transition-metal-catalyzed C-H activations.

Iron(III)-catalyzed Conia-ene cyclization of 2-alkynic 1,3-dicarbonyl compounds.

A cheap, simple, and effective FeCl(3)-catalyzed Conia-ene cyclization of 2-alkynic 1,3-dicarbonyl compounds was stereospecific to afford alkylidenecyclopentanes in (E)-isomers via the 5-exo-dig pathway. The 5-endo-dig and 6-exo-dig cyclizations were also possible, depending on the structure of the substrates.

A regio- and stereoselective synthesis of trisubstituted alkenes via gold(I)-catalyzed hydrophosphoryloxylation of haloalkynes.

A new stereoselective synthesis of trisubstituted alkenes is developed. Hydrophosphoryloxylation of haloalkynes provides Z-alkenyl halophosphates, which undergo Pd-catalyzed consecutive cross-coupling reactions to afford regio- and stereodefined trisubstituted alkenes.

Trifluoromethanesulfonic acid catalyzed isomerization of kinetic enol derivatives to the thermodynamically favored isomers.

Trifluoromethanesulfonic acid catalyzed isomerization of kinetic enol derivatives to the thermodynamically favored isomers was developed. Under the present conditions, kinetic enol phosphates, enol acetates and benzoates, and enol sulfonates were smoothly isomerized to produce the corresponding thermodynamically favored isomers in good to excellent yields.

Tungsten and molybdenum catalyst-mediated cyclisation of N-propargyl amides.

Tungsten and molybdenum catalysts were employed to promote the cyclisation of N-propargylic amides to afford the corresponding oxazolines or oxazines via 5-exo-dig or 6-endo-dig mode.

Synthesis of di-, tri-, and tetrasulfides through multifold carbon-sulfur cross-coupling reactions with indium tri(organothiolates) in a one-pot procedure.

Pd-catalyzed multifold (2-, 3-, and 4-fold) carbon-sulfur cross-coupling reaction of indium tri(organothiolates) with polybromonated aromatic and heteroaromatic compounds was developed in a one-pot procedure. Both 2,5-dibromopyridine and 2,6-dibromopyridine reacted with indium tri(organothiolates) (0.68 equiv) in the presence of 4 mol % of Pd(OAc)(2), 4.2 mol % of Xantphos, and 1 equiv of diisopropylethylamine (DIPEA), producing disulfides in good to excellent yields. These results indicate that indium tri(organothiolates) transfer all three alkyl- or arylthio groups attached to indium metal to electrophilic coupling partners. Indium tri(organothiolates) derived from alkyl thiol having a low boiling point, such as n-propyl, isopropyl, and tert-butyl thiol, acted as good nucleophilic coupling partners. In addition, indium tri(arylthiolates) derived from aryl thiols possessing an electron-withdrawing or -donating group on the aromatic ring participated well in the Pd-catalyzed multifold carbon-sulfur cross-coupling reaction. 4,4'-Dibromo-1,1'-biphenyl, 9,10-dibromoanthracene, 2,4-dibromoanisole, 2,7-dibromo-9,9-dimethylfluorene, 3,4-dibromothiophene, 2,3-dibromothiophene, 2,2'-bithiophene, 1,3,5-tribromobenzene, and 1,2,4,5-tetrabromobenzene were converted smoothly to the corresponding di-, tri-, and tetrasulfides.

Gold(I)-catalyzed addition of carboxylic acids to alkynes.

Au(I)-catalyzed hydroacyloxylation of alkynes with carboxylic acids is described. PPh3AuCl/AgPF6 catalyst affords the Markonikov addition products, whereas PPh3AuCl/AgOTf catalyst gives the more stable isomerized products via the Markonikov products.

Facile nucleophilic substitution of sulfonyl oxime ethers: an easy access to oxime ethers, carbonyl compounds and amines.

Sulfonyl oxime ethers undergo facile nucleophilic substitutions with various nucleophiles to yield the corresponding oxime ethers which provide an easy access to amines and carbonyl compounds.