Palladium-catalyzed Decarboxylative Coupling Reaction Research Articles

Selective Mono- and Dialkynylation of 1-Fluoro-2,2-diiodovinylarenes Using Pd-Catalyzed Decarboxylative Coupling Reactions.

Palladium-catalyzed decarboxylative coupling reactions using alkynoic acids and 1-fluoro-2,2-diiodovinylarenes provide mono- and dialkynylfluoroalkenes with high selectivity. When the reaction was conducted using DBU/DMSO, the hydrodeiodinated monoalkynylfluoroalkene product was formed, whereas performing the reaction using Et3N/THF gave the dialkynylfluoroalkene product. Both reaction conditions gave high yields of the desired enyne and endiyne products bearing fluorine atoms.

Synthesis of cis-5,5a,6,10b-Tetrahydroindeno[2,1-b]indoles through Palladium-Catalyzed Decarboxylative Coupling of Vinyl Benzoxazinanones with Arynes.

A novel palladium-catalyzed decarboxylative coupling reaction of vinyl benzoxazinanones with arynes which may feature an intramolecular nucleophilic attack of an amino group at the central carbon of π-allylpalladium intermediate has been developed. The cis-5,5a,6,10b-tetrahydroindeno[2,1-b]indoles were generated in moderate to good yields. One key to the success of the present reaction was to achieve comparable rates for the palladium-catalyzed decarboxylation and aryne formation steps.

Palladium-Catalyzed Decarboxylative Coupling of Alkynyl Carboxylic Acids and Alkenyl Tosylates for the Synthesis of Enynones.

A palladium-catalyzed decarboxylative coupling reaction was developed for the synthesis of 3-(1-alkynyl)-2-cyclohexen-1-ones. A variety of alkynyl carboxylic acids were coupled with 3-oxocyclohexenyl tosylates to afford the corresponding enynones in good to excellent yields. The developed catalytic system is phosphine free and showed good tolerance toward various functionalities such as chloride, cyano, nitro, ester, aldehyde, and alcohol groups. In addition, phenylpropiolic acid exhibited higher reactivity in the reaction with alkenyl toslyate than phenyl acetylene.

C1'-Azacycloalkyl Hexahydrocannabinols.

We report the design, synthesis, and biological evaluation of a novel class of cannabinergic ligands, namely C1'-azacycloalkyl hexahydrocannabinols. Our synthetic approaches utilize an advanced common chiral intermediate triflate from which all analogues could be derived. Key synthetic steps involve microwave-assisted Liebeskind-Srogl C-C cross-coupling and palladium-catalyzed decarboxylative coupling reactions. The C1'-N-methylazetidinyl and C1'-N-methylpyrrolidinyl analogues were found to be high affinity ligands for the CB1 and CB2 cannabinoid receptors.

Palladium-catalyzed decarboxylative coupling reaction with alkynyl carboxylic acids and arylsiloxanes

A decarboxylative coupling reaction for alkynyl carboxylic acids and arylsiloxanes was developed using a palladium catalyst. This method provided the desired coupled products in moderate to good yields by reacting the alkynyl carboxylic acids and arylsiloxanes with Pd(dba)2 (1.0mol%), 1,1-bis(diphenylphosphino)methane (1.0mol%), and AgF2 (2.0equiv) at 60°C for 6h.

ChemInform Abstract: Palladium‐Catalyzed Decarboxylative Trifluoroethylation of Aryl Alkynyl Carboxylic Acids.

A trifluoroethylation of alkynes through a palladium-catalyzed decarboxylative coupling reaction was developed. When alkynyl carboxylic acids and ICH2CF3 were allowed to react with [Pd(η3-allyl)Cl]2/XantPhos and Cs2CO3 in N,N-dimethylformamide (DMF) at 80 °C for 1 h, the desired products were formed in good yields. This catalytic system showed high functional group tolerance.

ChemInform Abstract: Synthesis of Novel Zerumbone Derivatives via Regioselective Palladium Catalyzed Decarboxylative Coupling Reaction: A New Class of α‐Glucosidase Inhibitors.

AbstractA strategy for the synthesis of novel zerumbone derivatives via a regioselective palladium catalyzed decarboxylative coupling reaction using arene carboxylic acids is described.

Palladium-Catalyzed Decarboxylative Trifluoroethylation of Aryl Alkynyl Carboxylic Acids

A trifluoroethylation of alkynes through a palladium-catalyzed decarboxylative coupling reaction was developed. When alkynyl carboxylic acids and ICH2CF3 were allowed to react with [Pd(η(3)-allyl)Cl]2/XantPhos and Cs2CO3 in N,N-dimethylformamide (DMF) at 80 °C for 1 h, the desired products were formed in good yields. This catalytic system showed high functional group tolerance.

A DFT study on palladium-catalyzed decarboxylative intramolecular aziridination reaction mechanism

The mechanism of palladium-catalyzed intramolecular decarboxylative aziridination reaction from 4H-isoxazol-5-one leading to 1-azabicyclo[3.1.0]hex-2-ene has been studied computationally with the aid of density functional theory (DFT). Full free energy profiles are computed for different reaction pathways. The catalytic cycle was found to include four steps: oxidative addition, decarboxylation, olefin insertion and reductive elimination. The DFT calculations indicated that the decarboxylation is the rate-determining step for palladium-catalyzed intramolecular decarboxylative aziridination reaction with an overall barrier of 32.9 kcal/mol from intermediate 4 to transition state TS6, which is in well agreement with previous calculations on palladium-catalyzed decarboxylative coupling reactions.

Ligand-free palladium-catalyzed decarboxylative coupling reactions of aryl iodides and alkynyl carboxylic acids

Pd-CNT nanocomposite was prepared from the composite of thiolated MWNT and Na2PdCl4. The palladium nanoparticles possess an average diameter of 2.9 nm with a narrow size distribution for the Pd-CNT. This Pd-CNT showed good activities in the coupling reactions of aryl iodides and aryl alkynyl carboxylic acids to produce the diaryl alkynes in good yields without any additional ligand.

Palladium-Catalyzed Decarboxylative Coupling of Alkynyl Carboxylic Acids with Benzyl Halides or Aryl Halides

The synthesis of internal benzyl alkynes and 1,2-diarylalkynes has been developed via palladium-catalyzed decarboxylative coupling reactions of alkynyl carboxylic acids with benzyl chlorides or aryl halides. In the presence of Pd(OAc)(2) and Xphos (L3), alkynyl carboxylic acids smoothly underwent the reaction with various benzyl halides, providing the corresponding benzyl alkynes in moderate to good yields. It is noteworthy that the optimal conditions are compatible with a wide range of aryl halides including less active aryl chlorides.

Palladium-Catalyzed Decarboxylative Coupling of Alkynyl Carboxylic Acids and Aryl Halides

2-Octynoic acid and phenylpropiolic acid were employed for the palladium-catalyzed decarboxylative coupling reaction and with a variety of aryl halides. The former needed 1,4-bis(diphenylphosphino)butane (dppb) as a ligand and the latter tri-tert-butylphosphine (P(t)Bu(3)), and both required 2 equiv of tetra-n-butylammonium fluoride (TBAF) for full conversion. These reactions showed high reactivities and tolerance of functional groups such as vinyl, ester, ether, ketone, and amine.

Development of a Decarboxylative Palladation Reaction and Its Use in a Heck‐Type Olefination of Arene Carboxylates.

The development of a palladium-catalyzed decarboxylative coupling reaction of arene carboxylates with olefinic substrates is described. The optimized procedure for decarboxylative palladation employs Pd(O2CCF3)2 as catalyst (0.2 equiv) in the presence of Ag2CO3 (3 equiv) in the solvent 5% DMSO-DMF and proceeds at temperatures of 80−120 °C with a wide range of arene carboxylates and alkenes as substrates. The process is proposed to proceed by an initial Ar-SE reaction involving ipso attack of an electrophilic Pd(II) intermediate on an arene carboxylate to form an arylpalladium(II) species with loss of carbon dioxide. This intermediate is then proposed to react with an olefinic substrate by steps common to the Heck coupling process. Reoxidation of the liberated Pd(0) in situ is proposed to establish the catalytic cycle.

Development of a decarboxylative palladation reaction and its use in a Heck-type olefination of arene carboxylates.

The development of a palladium-catalyzed decarboxylative coupling reaction of arene carboxylates with olefinic substrates is described. The optimized procedure for decarboxylative palladation employs Pd(O2CCF3)2 as catalyst (0.2 equiv) in the presence of Ag2CO3 (3 equiv) in the solvent 5% DMSO-DMF and proceeds at temperatures of 80-120 degrees C with a wide range of arene carboxylates and alkenes as substrates. The process is proposed to proceed by an initial Ar-SE reaction involving ipso attack of an electrophilic Pd(II) intermediate on an arene carboxylate to form an arylpalladium(II) species with loss of carbon dioxide. This intermediate is then proposed to react with an olefinic substrate by steps common to the Heck coupling process. Reoxidation of the liberated Pd(0) in situ is proposed to establish the catalytic cycle.