Bing-Tao Guan

Biaryl Construction via Ni-Catalyzed C-O Activation of Phenolic Carboxylates

Biaryl scaffolds were constructed via Ni-catalyzed aryl C-O activation by avoiding cleavage of the more reactive acyl C-O bond of aryl carboxylates. Now aryl esters, in general, can be successfully employed in cross-coupling reactions for the first time. The substrate scope and synthetic utility of the chemistry were demonstrated by the syntheses of more than 40 biaryls and by constructing complex organic molecules. Water was observed to play an important role in facilitating this transformation.

Cross-Coupling of Alkenyl/Aryl Carboxylates with Grignard Reagent via Fe-Catalyzed C−O Bond Activation

Iron-catalyzed cross-coupling of alkenyl/aryl carboxylates with primary alkyl Grignard reagent was described. This reaction brought a new family of electrophiles to iron catalysis. The combination of an inexpensive carboxylate electrophile and an iron catalyst would generate ample advantages.

Methylation of arenes via Ni-catalyzed aryl C-O/F activation

Aryl C-O and C-F can be transformed into C-Me via Ni-catalyzed coupling with MeMgBr under mild conditions.

Nickel-Catalyzed Efficient and Practical Suzuki−Miyaura Coupling of Alkenyl and Aryl Carbamates with Aryl Boroxines

Suzuki-Miyaura coupling of unactivated alkenyl carbamates is described to construct polysubstituted olefins. The developed process is also suitable for heteroaromatic and even electron-rich aromatic carbamates.

Direct Benzylic Alkylation via Ni-Catalyzed Selective Benzylic sp3 C−O Activation

This article demonstrates the first cross coupling of benzyl ether with Grignard reagents via Ni-catalyzed benzylic sp3 C−O activation with high efficiency and excellent chemoselectivity. Benzylic sp3 C−O and aryl sp2 C−O were differentiated, controlled by ligands.

Rare-earth-catalyzed C-H bond addition of pyridines to olefins.

An efficient and general protocol for the ortho-alkylation of pyridines via C-H addition to olefins has been developed, using cationic half-sandwich rare-earth catalysts, which provides an atom-economical method for the synthesis of alkylated pyridine derivatives. A wide range of pyridine and olefin substrates including α-olefins, styrenes, and conjugated dienes are compatible with the catalysts.

Direct Application of Phenolic Salts to Nickel‐Catalyzed Cross‐Coupling Reactions with Aryl Grignard Reagents

nickel D . -G . YU , B . J . L I , S . F. Z H E N G , B . T. G U A N , B . -Q . WA N G , Z . J . S H I * ( P E K IN G U N IVE R S I T Y, BE I J I N G , S T A T E KEY L A B O R A T O R Y O F O RG A N O M E T A L L I C C H E M I S T R Y, S H A N G H A I A N D S I C H U A N N O R M A L U N IVE R S IT Y, CH E N G D U , P. R . O F C H I N A ) Direct Application of Phenolic Salts to Nickel-Catalyzed Cross-Coupling Reactions with Aryl Grignard Reagents Angew. Chem. Int. Ed. 2010, 49, 4566-4570.

Carbon-carbon formation via Ni-catalyzed Suzuki-Miyaura coupling through C-CN bond cleavage of aryl nitrile.

The Suzuki-Miyaura coupling of aryl nitriles with aryl/alkenyl boronic esters is reported. With this method, the cyano group could be applied as a protecting group of arenes and finally as a leaving group to further construct polyaryl scaffolds.

Construction of Polysubstituted Olefins through Ni‐Catalyzed Direct Activation of Alkenyl CO of Substituted Alkenyl Acetates

Polysubstituted olefins broadly exist in natural and synthetic compounds, which can be constructed through various pathways, such as Wittig reaction, Julia–Lythgoe olefination, as well as coupling reactions. Among coupling reactions, the Suzuki–Miyaura coupling is one of the most efficient choices for alkenyl halides and their derivatives. However, due to the limited availability, high cost and low reactivity of the coupling partners, this method is not ideal. Although recent advances have promoted novel synthetic methods to construct such structural units from alkenyl methyl ethers via Ni-catalyzed Kumada cross-coupling, the difficulty to obtain starting materials and the poor compatibility of substituents, which arises from the use of Grignard reagents, limited its applications. Recently, the cleavage of “inert” aryl C–OMe, followed by cross-coupling with arylboronic acid derivatives, has been reported by Chatani and Kakiuchi with and without directing groups via Ru and Ni catalysis. Very recently, our group and Garg independently reported that aryl carboxylates could couple with arylboronic acid derivatives via Ni catalysis. Following studies indicated that coupling of aryl pivalates with organozinc reagents and alkyl Grignard reagents could take place under even milder conditions. This transformation was further expanded to alkenyl pivalates to afford styrene derivatives. However, to the best of our knowledge, there is no example to perform the Suzuki– Miyaura coupling starting from alkenyl acetates and arylboronic acid derivatives, although benzyl and allyl acetates have been applied in the corresponding coupling reactions via Pd catalysis. Herein, we reported for the first time a useful synthetic method to construct polysubstituted alkenes from easily available alkenyl acetates through Ni-catalyzed Suzuki–Miyaura coupling with arylboroxines. Generally, cross-coupling to afford aryl alkenes proceeded between aryl organoboron reagents and alkenyl triflates or phosphates due to their relatively high reactivities, which could be generated easily from carbonyl compounds with triflic anhydride or a chlorophosphate. However, the high cost, atomic economic waste, and relative difficulty of handling those chemicals limits this method. Compared with such a process, applying alkenyl acetates to the corresponding coupling reaction should be more general and easily controllable since alkenyl acetates could be easily produced through ester exchange (Scheme 1). Additionally, as reported previously, the methoxy group might react with organoboron compounds in the presence of Ni complexes, so the tolerance of methoxy group is also questionable in the [a] Prof. Dr. Z.-J. Shi Beijing National Laboratory of Molecular Sciences (BNLMS) PKU Green Chemistry Centre and Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education College of Chemistry and State Key Laboratory of Natural and Biomimetic Drugs Peking University, Beijing 100871 (China) Fax: (+86) 10-62760890 E-mail : zshi@pku.edu.cn [b] C.-L. Sun, Y. Wang, X. Zhou, Z.-H. Wu, B.-J. Li, B.-T. Guan, Prof. Dr. Z.-J. Shi Beijing National Laboratory of Molecular Sciences (BNLMS) PKU Green Chemistry Centre and Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education College of Chemistry and Molecular Engineering Peking University, Beijing 100871 (China) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.200902785. Scheme 1. New design on construction of polysubstituted olefins from ketones.

Biaryl construction through Kumada coupling with diaryl sulfates as one-by-one electrophiles under mild conditions.

Diaryl sulfates were successfully applied as one-by-one organo electrophiles in Kumada coupling to construct biaryls with the emission of harmless inorganic salts.