Copper-catalyzed extended Pummerer reactions of ketene dithioacetal monoxides with alkynyl sulfides and ynamides with an accompanying oxygen rearrangement.

The first examples of metal-catalyzed extended Pummerer reactions through the activation of sulfoxides are described. The copper-catalyzed reactions of ketene dithioacetal monoxides with alkynyl sulfides and ynamides provided a wide variety of γ,γ-disulfanyl-β,γ-unsaturated carbonyl compounds with an accompanying oxygen rearrangement. The products can be easily converted into 1,4-dicarbonyl compounds and substituted heteroaromatics.

Synthesis of alkylidenecyclopropanes by palladium-catalyzed reaction of propargyl-substituted malonate esters with aryl halides by anti-carbopalladation pathway.

Palladium-catalyzed arylative cyclization of propargyl-substituted malonate esters with aryl halides offers a stereoselective approach to alkylidenecyclopropanes. The reaction proceeds by an anti-carbopalladation pathway, which guarantees the exclusive stereocontrol of the resulting double bond. The highly strained as well as densely substituted skeletons of the products facilitate further versatile transformations, which underscores the importance of the products as synthetic intermediates.

Intermolecular reductive radical addition to 2-(2,2,2-trifluoroethylidene)-1,3-dithiane 1-oxide: experimental and theoretical studies.

Tin hydride mediated radical addition of organic halide to 2-(2,2,2-trifluoroethylidene)-1,3-dithiane 1-oxide has been devised. The reaction is equivalent to an unrealizable radical addition to trifluoromethylketene, providing useful α-trifluoromethyl carbonyl equivalents. The trifluoromethyl and the sulfoxide groups of the substrate play key roles for the success of the radical addition, lowering the barrier of the radical addition step and controlling the stereoselectivity of the reaction, which DFT calculations have elucidated.

Reaction pathway of methylenation of carbonyl compounds with bis(iodozincio)methane.

About 40 years have passed since methylene dizinc reagent was discovered as a substitute for Wittig reagent. Density functional theory (DFT) calculations have been performed to understand the reaction pathways of methylenation of carbonyl compounds with bis(iodozincio)methane. The present computational/theoretical study concluded that the methylenation reaction with gem-dizinc reagent proceeds as a two-step reaction, that is, methylene addition (RDS) and olefination.

Synthesis of 3-trifluoromethylbenzo[b]furans from phenols via direct ortho functionalization by extended Pummerer reaction.

A concise and diversity-oriented route to trifluoromethylbenzo[b]furans has been devised. A variety of phenols are directly converted to the corresponding 2-methylthio-3-trifluoromethylbenzo[b]furans by new triflic-anhydride-mediated extended Pummerer annulation reactions with trifluoromethylketene dithioacetal monoxide. The methylthio group of the products undergoes further transformations, which increase the diversity of available trifluoromethylbenzo[b]furans.

Cobalt-catalyzed addition of styrylboronic acids to 2-vinylpyridine derivatives.

Treatment of 2-vinyl nitrogen-containing heteroaromatic compounds with styrylboronic acid in the presence of a cobalt catalyst and a base results in an addition reaction to afford the corresponding 4-phenyl-3-butenyl heteroarenes. The adjacent nitrogen atom is essential for the promotion of the reaction because the nitrogen accelerates the addition of the styryl cobalt species, generated by transmetalation, onto the vinyl group. The reaction represents a rare example of cobalt catalysis in the reactions of organoboronic acids.

Rhodium-catalyzed arylzincation of terminal allenes providing allylzinc reagents and its application to versatile three-component coupling reaction.

Rhodium-catalyzed regioselective arylzincation of terminal allenes affords synthetically useful functionalized allylzinc reagents. The allylzinc reagents react with a variety of electrophiles such as acetonitrile, offering a more versatile three-component coupling reaction.

Palladium-catalyzed allylation of aryl halides with homoallyl alcohols bearing a trisubstituted double bond: application to chirality transfer from hydroxylated carbon to benzylic one.

A facile route to homoallyl alcohols bearing a trisubstituted double bond has been devised. The palladium-catalyzed reactions of aryl halides with the alcohols thus synthesized result in regiospecific allyl transfer from the alcohols to aryl halides via retro-allylation, providing allylarenes having two substituents at the 1 and 2 positions of the allyl moiety. Optically active homoallyl alcohols transfer their chirality at the hydroxylated carbon to the benzylic carbon of the product.

Silver-catalyzed benzylation and allylation of tertiary alkyl bromides with organozinc reagents.

Silver salts catalyze the benzylation and allylation of tertiary alkyl bromides with organozinc reagents. The reactions create quaternary carbon centers efficiently. Treatment of gem-dibromoalkanes with benzylic or allylic zinc reagents under silver catalysis leads to dibenzylation or diallylation.

Nickel-catalyzed arylative ring-opening of 3-methylenecycloalkane-1,1-dicarboxylates.

An arylative ring-opening reaction of cyclic allylmalonates with arylzinc reagents under nickel catalysis has been developed. Upon the ring-opening sp(3)C-sp(3)C bond cleavage, the allylic moiety serves as an allylic electrophile to react with arylzinc reagents. Simultaneously, the malonate moiety is converted to the corresponding zinc enolate, which can react further with electrophiles.

Synthesis of 2-indolylphosphines by palladium-catalyzed annulation of 1-alkynylphosphine sulfides with 2-iodoanilines.

Palladium-catalyzed annulation of 1-alkynylphosphine sulfides with 2-iodoanilines followed by desulfidation affords 3-substituted 2-indolylphosphines. This annulation/desulfidation sequential protocol offers a conceptually new approach to bulky heteroarylphosphines.

1-Alkynylphosphines and their derivatives as key starting materials in creating new phosphines.

This Focus Review summarizes transformations of 1-alkynylphosphines and their derivatives directed toward the synthesis of new phosphines. Owing to the importance of organophosphines as ligands for transition metal catalysts, development of efficient methods for the synthesis of new phosphines is quite important. 1-Alkynylphosphines and their derivatives have been emerging as useful precursors for the creation of new phosphines.

Palladium-catalysed arylative cyclisation of N-allylacetamides with aryl halides yielding benzyl-substituted oxazolines.

Treatment of N-allylacetamide with aryl halide in the presence of sodium t-butoxide and a palladium catalyst leads to arylative cyclisation to provide the corresponding benzyl-substituted oxazoline in high yield.

Palladium-catalyzed preparation of silyl enolates from alpha,beta-unsaturated ketones or cyclopropyl ketones with hydrosilanes.

Alpha,beta-unsaturated ketones and cyclopropyl ketones undergo palladium-catalyzed hydrosilylation with hydrosilanes to yield (Z)-silyl enolates.

Cobalt-catalyzed isomerization of 1-alkenes to (E)-2-alkenes with dimethylphenylsilylmethylmagnesium chloride and its application to the stereoselective synthesis of (E)-alkenylsilanes.

Treatment of 1-alkenes with dimethylphenylsilylmethylmagnesium chloride in the presence of a cobalt-NHC complex in dioxane at 50 degrees C or higher provides the corresponding (E)-2-alkenes selectively. The isomerization is applicable to the stereoselective synthesis of (E)-crotylsilanes and (E)-1-propenylsilanes from the corresponding homoallylsilanes and allylsilanes, respectively.

Cobalt-catalyzed arylzincation of alkynes.

Cobalt(II) bromide catalyzes arylzincation of alkynes with arylzinc iodide x lithium chloride complexes in acetonitrile. The scope of the arylzincation is wide enough to use unfunctionalized alkynes, such as 6-dodecyne, as well as arylacetylenes. The inherent functional group compatibility of arylzinc reagents allows preparation of various functionalized styrene derivatives.