Addition Of Arylboronic Acids Research Articles

Palladium catalyzed synthesis of mandelate derivatives from arylboronic acids and glyoxylate hemiacetals

NHC-coordinated cyclometalated palladium(II) catalyzed addition of arylboronic acids to methyl 2-hydroxy-2-methoxyacetate gave corresponding various functionalized methyl mandelate derivatives in good yields.

Rhodium-Catalyzed Addition of Aryl Boronic Acids to 2,2-Disubstituted Malononitriles.

β-Ketonitriles bearing a quaternary carbon at the 2-position were prepared through Rh-catalyzed addition of aryl boronic acids to 2,2-disubstituted malononitriles. In contrast to the previously described transnitrilative cyanation of aryl boronic acids with dialkylmalononitriles, the present reaction avoids retro-Thorpe collapse of the intermediate addition product through the use of a milder base. The reaction was amenable to a variety of aryl boronic acids and disubstituted malononitriles, providing a diverse array of β-ketonitriles. The products could be further derivatized to valuable chiral α,α-disubstituted-β-aminonitriles through addition reactions to the corresponding N-tert-butanesulfinyl imines.

Rhodium‐Catalyzed Addition of Aryl Boronic Acids to 2,2‐Disubstituted Malononitriles

Abstractβ‐Ketonitriles bearing a quaternary carbon at the 2‐position were prepared through Rh‐catalyzed addition of aryl boronic acids to 2,2‐disubstituted malononitriles. In contrast to the previously described transnitrilative cyanation of aryl boronic acids with dialkylmalononitriles, the present reaction avoids retro‐Thorpe collapse of the intermediate addition product through the use of a milder base. The reaction was amenable to a variety of aryl boronic acids and disubstituted malononitriles, providing a diverse array of β‐ketonitriles. The products could be further derivatized to valuable chiral α,α‐disubstituted‐β‐aminonitriles through addition reactions to the corresponding N‐tert‐butanesulfinyl imines.

Enantioselective Three-Component Assembly of β'-Aryl Enones Using a Rhodium-Catalyzed Alkyne Hydroacylation/Aryl Boronic Acid Conjugate Addition Sequence.

Rhodium-catalyzed alkyne hydroacylation using alkyl β-S-aldehydes, enantioselective rhodium-catalyzed aryl boronic acid conjugate addition, and sulfide elimination are combined in sequence to provide β'-aryl enones. The reaction sequence is efficient and delivers highly functionalized products with excellent levels of enantiocontrol. Good variation of the three reaction components is demonstrated. The sequence corresponds to the formal regio- and enantioselective monoconjugate addition of aryl boronic acids to dienones.

In situ generated cationic Pd(II)/bipyridine-catalyzed addition of arylboronic acids to N -sulfonyl-arylaldimines

Abstract An in situ generated cationic Pd(II)/bipyridine-catalyzed nucleophilic addition of arylboronic acids to N -sulfonyl arylaldimines was developed and optimized, and the reaction was proceeded highly efficiently and conveniently in CH 3 NO 2 . A series of arylboronic acids and N -sulfonyl arylaldimines were surveyed, and 12 of 13 examples gave 90∼96% yields.

Modified Amino Acid‐Derived Phosphine‐Imine Ligands for Palladium‐Catalyzed Asymmetric Arylation of Cyclic N‐Sulfonyl Imines

AbstractA series of chiral phosphine‐imine ligands were synthesized starting with α‐amino acids and examined for palladium‐catalyzed asymmetric addition of arylboronic acids to cyclic N‐sulfonyl imines. High catalytic activities (up to 99% yield) and high enantioselectivities (up to 98% ee) were achieved for cyclic N‐sulfonyl aldimines and ketimines with five and six‐membered ring structures.magnified image

Palladium‐Catalyzed Addition of Arylboronic Acids to para‐ Quinone Methides for Preparation of Diarylacetates

AbstractA palladium‐catalyzed addition of arylboronic acids to para‐quinone methides has been developed. The catalytic system employing 4,4′‐dimethoxy‐2,2′‐bipyridine (DMeO‐BPy) as ligand and trifluoroethanol (TFE) as solvent provides diarylacetate products in high yields. A wide range of functionalized arylboronic acids can be used and the method tolerates some variation in the scope of the para‐quinone methides.magnified image

Ni(ii)-catalyzed asymmetric addition of arylboronic acids to cyclic imines.

A Ni(ii)-catalyzed asymmetric addition of arylboronic acids to cyclic aldimines and ketimines is reported. Our tropos phosphine-oxazoline biphenyl ligand is crucial for the high catalytic activity, which coordinates to Ni(ii) to form a complex with a single axial configuration. The desired chiral amine products could be prepared with excellent yields (up to 99%) and enantioselectivities (up to 99.8%) under mild reaction conditions.

Ni-Catalyzed regio- and stereoselective addition of arylboronic acids to terminal alkynes with a directing group tether.

Addition of arylboronic acids to directing group tethered acetylenes in a regio and stereoselective manner using an inexpensive catalytic system is achieved for the first time to access highly sought after allyl/homoallyl alcohol/amine units. The apparent vinylnickel intermediate was successfully trapped by the Michael electrophiles to get defined tri- and tetra-substituted olefins. An interesting selectivity switch was observed with internal alkynes.

Palladium-catalyzed conjugate addition of arylboronic acids to 2-substituted chromones in aqueous media

Palladium-catalyzed conjugate additions of arylboronic acids to 2-alkylchromones are reported. The conjugate additions occur in aqueous media in the presence of a catalyst generated from palladium trifluoroacetate and 1,10-phenanthroline, and the flavanone derivatives containing a fully-substituted carbon center are formed in up to 90% yield.

Axial Tri-tert-butylphosphane Coordination to Rh2(OAc)4: Synthesis, Structure, and Catalytic Studies

The introduction of strong σ-donor axial ligands to the Rh–Rh metal bond has been utilized as an effective way to provide new chemical reactivities to bimetallic dirhodium(II) complexes. In this report, Rh2(OAc)4 complexes with axial bulky alkylphosphane ligands (PR3), in particular P(t-Bu)3, were prepared and characterized. The net σ-donation from the PR3 to the Rh–Rh bond is the result of the competition between the electron-donating ability of the R group and the steric profile of the PR3 at the Rh2 core. Analysis of the crystal structure data showed that the strong σ-donor P(t-Bu)3 coordinates to the rhodium with an amount of σ-donation to the rhodium similar to that of the aryl phosphane ligand PPh3, but has an unusually long Rh–P bond distance (2.663 A). During catalytic trials to synthesize 3-aryl-3-hydroxy-2-oxindole by the addition of arylboronic acids to isatin derivatives, this longer Rh–P bond distance in Rh2(OAc)4(P(t-Bu)3)2 (Cat-1) facilitates substitution of one of the axial phosphane ligan...

ChemInform Abstract: Pd(II)/Bipyridine Catalyzed Conjugate Addition of Arylboronic Acids to α,β‐Unsaturated Amides.

Abstract The Pd(II)/bipyridine-catalyzed conjugate addition of arylboronic acid to α,β-unsaturated amides was developed and optimized, and the reaction was proceeded smoothly in air. A series of arylboronic acid and α,β-unsaturated amide substrates were surveyed, and modest to excellent yields were given.

ChemInform Abstract: Rhodium‐Catalyzed Asymmetric Intramolecular Addition of Arylboronic Acids to Ketones: Catalytic Enantioselective Access to 3‐Hydroxy‐2,3‐dihydrobenzofurans Bearing a Tetrasubstituted Carbon Stereocenter.

A highly enantioselective rhodium-catalyzed intramolecular addition of arylboronic acids to unactivated ketones has been developed. By employing a simple, chiral sulfur-based branched olefin as the ligand, the reaction occurs efficiently under mild conditions. A wide range of chiral 3-hydroxy-2,3-dihydrobenzofurans bearing a tetrasubstituted stereocenter at C-3 position can be obtained in high yields (up to 98%) with excellent enantiomeric excesses (up to 98% ee).

Supported palladium nanoparticles: A general sustainable catalyst for microwave enhanced carbon-carbon coupling reactions

Synergism between nanocatalysts and microwave heating has emerged as a tool for sustainable organic synthesis. In the present investigation scope of palladium nanoparticle for ligand free carbon-carbon coupling reactions namely Suzuki, Hiyama, Heck and Sonogashira under microwave heating is investigated. Palladium nanoparticles of less than 10nm dimension were impregnated onto a commercially available, non-functional, microporous polystyrene resin and were characterized by UV–vis spectroscopy, HRTEM attached with EDX, powder X-ray Diffraction (XRD) and ICP-AES. Highly pure coupled products in various reactions were obtained in 6–35min using microwave heating in closed vials using benign mixed low boiling solvents, which otherwise require 4–30h of inert atmosphere under conventional heating. Reaction parameters such as temperature, time and concentration of catalyst were optimized and catalyst was successfully recycled five to six times without any noticeable leaching or decrease in performance. Post reaction TEM analysis showed that size of the nanoparticles was still in the range of 3–10nm. The catalyst was successfully used to synthesize asymmetric terphenyls in a single pot by sequential addition of aryl boronic acids.

ChemInform Abstract: Two Phenyls Are Better Than One or Three: Synthesis and Application of Terminal Olefin‐Oxazoline (TOlefOx) Ligands.

AbstractA novel terminal olefin‐oxazoline ligand containing two diphenylmethyl groups is used in the highly enantioselective rhodium‐catalyzed conjugate addition of aryl boronic acids to enones.

ChemInform Abstract: Rhodium‐Catalyzed Enantioselective Arylation of N‐Substituted α,β‐Unsaturated γ‐Lactams: Preparation of Chiral 4‐Aryl‐2‐pyrrolidones.

AbstractA highly stereoselective conjugate addition of arylboronic acids and N‐substituted α,β‐unsaturated γ‐lactams provides the chiral title pyrrolidones.

ChemInform Abstract: Highly Diastereoselective 1,6‐Conjugate Addition of Arylboronic Acids to Securinine.

AbstractRhodium catalysis provides access to the single diastereomers of the regioselective C15‐arylation products of securinine in good yields.

Synthesis and evaluation of C2-symmetric bis-sulfinamides as effective ligands in rhodium catalyzed addition of arylboronic acids to cycloalkenones

Synthesis of novel C2-symmetric 1,2- 1,3- and 1,4- bis-sulfinamides and their use as effective ligands in rhodium (I) catalyzed asymmetric conjugate addition of arylboronic acids to cyclohexenone and cyclopentenones is described. C2-symmetry as well as chirality at the sulfur center in the ligand is crucial for the high enantioselectivity in the 1,4-addition reaction. It was also observed that the conjugate addition proceeded with good selectivity with Wilkinson's catalyst as the rhodium source.

Enantioselective Nickel-Catalyzed anti-Carbometallative Cyclizations of Alkynyl Electrophiles Enabled by Reversible Alkenylnickel E/Z Isomerization.

Nickel-catalyzed additions of arylboronic acids to alkynes, followed by enantioselective cyclizations of the alkenylnickel species onto tethered ketones or enones, are reported. These reactions are reliant upon the formal anti-carbonickelation of the alkyne, which is postulated to occur by the reversible E/Z isomerization of an alkenylnickel species.

ChemInform Abstract: Highly Regioselective Introduction of Aryl Substituents via Asymmetric 1,4‐Addition of Boronic Acids to Linear α,β,γ,δ‐Unsaturated Ketones.

An efficient palladium(II)-catalyzed regioselective asymmetric 1,4-conjugate addition of arylboronic acids to linear α,β,γ,δ-unsaturated ketones is developed using phosphapalladacycle catalysts. The relevant 1,4-products were obtained exclusively with perfect regioselectivity, appreciable yields, and enantioselectivities. A wide range of dienone substrates as well as substituted arylboronic acids are tolerated in this protocol which proceeds at room temperature.