Xi Lu

Copper-Catalyzed/Promoted Cross-coupling of gem-Diborylalkanes with Nonactivated Primary Alkyl Halides: An Alternative Route to Alkylboronic Esters

The first copper-catalyzed/promoted sp(3)-C Suzuki-Miyaura coupling reaction of gem-diborylalkanes with nonactivated electrophilic reagents is reported. Not only 1, 1-diborylalkanes but also some other gem-diborylalkanes can be coupled with nonactivated primary alkyl halides, offering a new method for sp(3)C-sp(3)C bond formation and, simultaneously, providing a new strategy for the synthesis of alkylboronic esters.

Copper-Catalyzed SN2′-Selective Allylic Substitution Reaction of gem-Diborylalkanes

A Cu/(NHC)-catalyzed SN2-selective substitution reaction of allylic electrophiles with gem-diborylalkanes is reported. Different substituted gem-diborylalkanes and allylic electrophiles can be employed in this reaction, and various synthetic valuable functional groups can be tolerated. The asymmetric version of this reaction was initially researched with chiral N-heterocyclic carbene (NHC) ligands.

Copper‐Catalyzed Reductive Cross‐Coupling of Nonactivated Alkyl Tosylates and Mesylates with Alkyl and Aryl Bromides

A copper-catalyzed reductive cross-coupling reaction of nonactivated alkyl tosylates and mesylates with alkyl and aryl bromides was developed. It provides a practical method for efficient and cost-effective construction of aryl-alkyl and alkyl-alkyl Cuf8ffC bonds with stereocontrol from readily available substrates. When used in an intramolecular fashion, the reaction enables convenient access to various substituted carbo- or heterocycles, such as 2,3-dihydrobenzofuran and benzochromene derivatives.

Pd-catalyzed cross-coupling of 1,1-diborylalkanes with aryl triflates

The Pd-catalyzed synthesis of benzylboronic esters through coupling of aryl triflates with 1,1-diborylalkane under ambient conditions is described. Varieties of primary and secondary arylboronic esters could be successfully synthesized by this strategy. Competitive reaction demonstrated that aryl C–OTf bond was more inert than aryl bromide.

Rhodium(III)-Catalyzed Directed C–H Coupling with Methyl Trifluoroacrylate: Diverse Synthesis of Fluoroalkenes and Heterocycles

An example of Rh-catalyzed C-H activation with methyl trifluoroacrylate for the synthesis of fluoroolefins and heterocycles (benzoindolizines) is reported. The types of products were determined by the directing group. The benzoindolizines and fluoroolefins were obtained by using pyridine and pyrazole as the directing group, correspondingly. These transformations present a number of advantages, such as oxidant-free reaction conditions and broad functional group tolerance. Moreover, this reaction greatly extends the application of fluoroolefins.

Copper-Catalyzed Alkynylboration of Alkenes with Diboron Reagents and Bromoalkynes

An efficient method for the synthesis of homopropargylboronates by copper-catalyzed alkynylboration of alkenes with diboron reagents and bromoalkynes has been developed. The alkynylboration reaction features high selectivity and efficiency, mild reaction conditions, wide substrate scope, and functional-group compatibility, and is a highly attractive complement to existing methods for the synthesis of homopropargylboronates. Both the boryl and alkynyl groups are good potential functional groups for the subsequent manipulations that provide access to a variety of important molecule structures.

Copper-Catalyzed Reagent-Controlled Regioselective Cyanoborylation of Vinylarenes

A copper-catalyzed borylation/benzylic cyanation of vinylarenes whose regioselectivity is seemly common but scarcely achieved is reported. This unprecedented regioselectivity is realized through a structure-distinctive cyanating reagent, dimethylmalononitrile. This reaction can be applied to both π-extended and simple vinylarenes with various diboron reagents, and it exhibits good functional group compatibility. With the ample transformations of cyano and boronate groups, this reaction provides expedient access to complex organic structures.

Exploration of Biaryl Carboxylic Acids as Proton Shuttles for the Selective Functionalization of Indole C–H Bonds

A survey of diversely substituted 2-arylbenzoic acids were synthesized and tested for use as proton shuttle in the direct arylation of indoles with bromobenzenes. It was found that 3-ethoxy-2-phenylbenzoic acid gives superior yield and selectivity for this class of substrates.