Enantioselective rhodium-catalyzed addition of arylboronic acids to alkenylheteroarenes

In the presence of a rhodium complex containing a newly developed chiral diene ligand, alkenes activated by a range of π-deficient or π-excessive heteroarenes engage in highly enantioselective conjugate additions with various arylboronic acids.     

Enantioselective rhodium-catalyzed addition of arylboronic acids to aldehydes using chiral spiro monophosphite ligands

[reaction: see text] Highly efficient rhodium-catalyzed asymmetric addition of arylboronic acids to aldehydes has been realized by using chiral spiro monophosphite ligands, affording diarylmethanols in excellent yields and good enantiomeric excesses.     

Highly enantioselective rhodium-catalyzed conjugate addition of arylboronic acids to enones at room temperature

The rhodium-phosphoramidite-catalyzed asymmetric conjugate addition of arylboronic acids to enones proceeds at room temperature using [Rh(OH)(cod)]₂ or [RhCl(cod)]₂/KOH as stable and readily available catalyst precursors.     

Novel hexadentate imidazolium salts in the rhodium-catalyzed addition of arylboronic acids to aldehydes

Four novel hexadentate imidazolium salts were synthesized from hexakis(bromomethyl)benzene and 1-substituted imidazole. The arylation of aldehydes with arylboronic acids was effected conveniently and in high yields by a catalyst system generated in situ from these hexadentate imidazolium salts, [Rh(COD)Cl]₂ and a base.     

Bipyridyl-based diphosphine as an efficient ligand in the rhodium-catalyzed asymmetric conjugate addition of arylboronic acids to α,β-unsaturated ketones

Reactions of α,β-unsaturated ketones with excess arylboronic acids in the presence of a rhodium catalyst generated in situ from Rh(acac)(C₂H₄) and (S)-P-Phos in dioxane/water at 100°C gave high yields of the corresponding products in up to 99% ee.     

Asymmetric synthesis of protected arylglycines by rhodium-catalyzed addition of arylboronic acids to N-tert-butanesulfinyl imino esters

A new method for the Rh(I)-catalyzed addition of arylboronic acids to N-tert-butanesulfinyl imino esters has been developed for the asymmetric synthesis of arylglycine derivatives. This method provides high yields (61-90%) and diastereoselectivities (>98:2) for a variety of functionalized arylboronic acids. The N-sulfinyl arylglycine ester products are versatile intermediates for further transformations, including selective protecting group removal, conversion to beta-amino alcohols, and direct incorporation into peptides.     

A simple rhodium-catalyzed addition reaction of aldehydes with arylboronic acids in aqueous γ-valerolactone

A simple rhodium-catalyzed addition reaction of aldehydes with arylboronic acids in aqueous γ-valerolactone provides the corresponding benzylic alcohols in moderate to good yields. Other organoboron reagents (boronic esters, aryl-trifluoroborates, etc.) also showed good compatibilities, albeit with relatively lower yields.     

The first examples of rhodium-catalyzed 1,4-conjugate addition reactions of arylboronic acids with ethenesulfonamides

An unprecedented rhodium-catalyzed 1,4-conjugate addition of arylboronic acids with ethenesulfonamides resulting in the corresponding 2-arylethanesulfonamides is described. The amino substituent, the applied arylboronic acid, the type of Rh-catalyst, and the experimental conditions all affected the reaction outcome.     

The synthesis of unsaturated trifluoromethyl ketones by regioselective organocuprate addition to acetylemic trifluoromethyl ketones

Regiospecific and stereoselective synthesis of unsaturated trifluoromethyl ketones has been accomplished by the addition of higher order cyano cuprates to acetylenic trifluoromethyl ketones.     

Catalytic enantioselective addition of diethylzinc to trifluoromethyl ketones

A procedure for nucleophilic addition of diethylzinc to trifluoromethyl ketones was developed. The TMEDA-catalyzed method converts aromatic substrates to the corresponding 2-aryl-1,1,1-trifluorobutan-2-ols in up to 99% yield, and it is also applicable to less reactive aliphatic ketones if stoichiometric ligand amounts are employed. The first asymmetric variant producing tertiary alcohols with up to 61% ee when TBOX is used as catalyst is described.     

Palladium-catalyzed addition of arylboronic acids to aldehydes

[reaction: see text] Arylboronic acids react with aldehydes in the presence of a base and a catalytic amount of a palladium(0) complex with chloroform, affording the corresponding secondary alcohols in good yields. General palladium complexes have no catalytic activity without chloroform. Chloroform is essential for this reaction, and palladium complex that was prepared from Pd(PPh3)4 with CHCl3 showed good catalytic acitivity as well.     

Rhodium-catalysed addition of arylboronic acids to oxabenzonorbornadienes

The facile addition reaction of boronic acids to oxabenzonorbornadienes was achieved using a catalytic amount of a rhodium(I) complex having P(OEt)3 ligands, affording cis-2-aryl-1,2-dihydro-1-naphthol stereoselectively, and in good yield without concomitant deboronation of the boronic acid.     

Palladium-catalyzed addition of arylboronic acids to isocyanates

The addition of arylboronic acids to isocyanates catalyzed by palladium acetate in the presence of triphenylphosphine as the ligand is described.     

Copper-mediated trifluoromethylation of arylboronic acids by trifluoromethyl sulfonium salts

The ligand-free trifluoromethylation of arylboronic acids with a [Ph(2)SCF(3)](+)[OTf](-)/Cu(0) system has been carefully investigated. Aryl-, alkenyl- and heteroarylboronic acids with a variety of functional groups were suitable substrates for this reaction. It is suggested that a CuCF(3) species is formed under the reaction conditions.     

Cu-catalyzed stereoselective conjugate addition of arylboronic acids to alkynoates

The CuOAc-catalyzed reaction of internal alkynoates with arylboronic acids proceeded under mild conditions to yield trisubstituted cinnamates stereoselectively.