Juan Zhang

Bio: Juan Zhang is an academic researcher from Chongqing University. The author has contributed to research in topics: Borylation & Silylation. The author has an hindex of 5, co-authored 8 publications receiving 53 citations. Previous affiliations of Juan Zhang include Taiyuan University of Technology.

Iron-Catalyzed Borylation and Silylation of Unactivated Tertiary, Secondary, and Primary Alkyl Chlorides

Abstract: Herein, we describe an iron-catalyzed borylation and silylation of unactivated alkyl chlorides, delivering the tertiary, secondary, and primary alkylboronic esters, and secondary, primary alkylsila...

Strategies for targeting undruggable targets.

Abstract: Introduction Undruggable targets refer to clinically meaningful therapeutic targets that are 'difficult to drug' or 'yet to be drugged' via traditional approaches. Featuring characteristics of lacking defined ligand-binding pockets, non-catalytic protein-protein interaction functional modes and less-investigated 3D structures, these undruggable targets have been targeted with novel therapeutic entities developed with the progress of unconventional drug discovery approaches, such as targeted degradation molecules and display technologies. Area covered This review first presents the concept of 'undruggable' exemplified by RAS and other targets. Next, detailed strategies are illustrated in two aspects: innovation of therapeutic entities and development of unconventional drug discovery technologies. Finally, case studies covering typical undruggable targets (Bcl-2, p53, and RAS) are depicted to further demonstrate the feasibility of the strategies and entities above. Expert opinion Targeting the undruggable expands the scope of therapeutically reachable targets. Consequently, it represents the drug discovery frontier. Biomedical studies are capable of dissecting disease mechanisms, thus broadening the list of undruggable targets. Encouraged by the recent approval of the KRAS inhibitor Sotorasib, we believe that merging multiple discovery approaches and exploiting various novel therapeutic entities would pave the way for dealing with more 'undruggable' targets in the future.

Transformations of Less-Activated Phenols and Phenol Derivatives via C-O Cleavage.

Abstract: Employing phenols and phenol derivatives as electrophiles for cross-coupling reactions has numerous advantages over commonly used aryl halides in terms of environmental-friendliness and sustainability. In the early stage of discovering such transformations, most efforts have been devoted to utilizing highly activated sulfonate types of phenol derivatives (e.g., OTf, OTs, etc.), which have similar reactivities to the corresponding aryl halides. However, a continuing scientific challenge is how to achieve the direct C-O functionalizations of relatively less-activated phenol derivatives more efficiently. In this review, we will focus on the recent updates on the C-O functionalizations of less-activated phenol derivatives, from aryl carboxylates (e.g., pivalates, acetates, etc.), aryl carbamates and carbonates, to aryl ethers (anisoles, diaryl ethers, aryl pyridyl ethers, aryl silyl ethers), to phenolate salts, and ultimately to simply unprotected phenols, sorted by the types of bond formations. Both transition-metal-catalyzed and transition-metal-free protocols will be covered and discussed in detail. Instead, the C-O functionalizations of aryl sulfonates will not be covered extensively unless they are closely related, due to their high reactivity. Since aryl ethers and phenols represent the main linkages or units in lignin biomass, the successes of such transformations will potentially make major contributions to the direct lignin biomass upgrading and depolymerization.

First-Row d-Block Element-Catalyzed Carbon-Boron Bond Formation and Related Processes.

Abstract: Organoboron reagents represent a unique class of compounds because of their utility in modern synthetic organic chemistry, often affording unprecedented reactivity. The transformation of the carbon-boron bond into a carbon-X (X = C, N, and O) bond in a stereocontrolled fashion has become invaluable in medicinal chemistry, agrochemistry, and natural products chemistry as well as materials science. Over the past decade, first-row d-block transition metals have become increasingly widely used as catalysts for the formation of a carbon-boron bond, a transformation traditionally catalyzed by expensive precious metals. This recent focus on alternative transition metals has enabled growth in fundamental methods in organoboron chemistry. This review surveys the current state-of-the-art in the use of first-row d-block element-based catalysts for the formation of carbon-boron bonds.

Iron-Catalyzed CN Cross-Coupling ofSulfoximines with Aryl Iodides

Abstract: An inexpensive and experimentally simple, iron-catalyzed N-arylation reaction of NH- sulfoximines with aryl iodides is reported. This com- plementary method to the known palladium- and copper-catalyzed ones features the use of a combi- nation of environmentally friendly FeCl3 and N,N'- dimethylethylenediamine (DMEDA) as catalytic system and allows the efficient preparation of vari- ous N-arylsulfoximines in high yields.

Electrochemical Borylation of Alkyl Halides: Fast, Scalable Access to Alkyl Boronic Esters.

Abstract: Herein, a fast, scalable, and transition-metal-free borylation of alkyl halides (X = I, Br, Cl) enabled by electroreduction is reported. This process provides an efficient and practical access to primary, secondary, and tertiary boronic esters at a high current. More than 70 examples, including the late-stage borylation of natural products and drug derivatives, are furnished at room temperature, thereby demonstrating the broad utility and functional-group tolerance of this protocol. Mechanistic studies disclosed that B2cat2 serves as both a reagent and a cathodic mediator, enabling electroreduction of difficult-to-reduce alkyl bromides or chlorides at a low potential.

Regio- and Stereoselective Hydrosilylation of Alkynes Catalyzed by Three-Coordinate Cobalt(I) Alkyl and Silyl Complexes

Abstract: A three-coordinate cobalt(I) complex exhibits high catalytic efficiency and selectivity as well as good functional group compatibility in alkyne hydrosilylation. [Co(IAd)(PPh3)(CH2TMS)] (1) (IAd = 1,3-diadamantylimidazol-2-ylidene) facilitates regio- and stereoselective hydrosilylation of terminal, symmetrical internal, and trimethylsilyl-substituted unsymmetrical internal alkynes to produce single hydrosilylation products in the forms of beta-(E)-silylalkenes, (E)-silylalkenes, and (Z)-alpha,alpha-disilylalkenes, respectively, in high yields. The comparable catalytic efficiency and selectivity of the Co(I) silyl complex [Co(IAd)(PPh3)(SiHPh2)] that was prepared from the reaction of 1 with H2SiPh2, and the isolation of an alkyne Co(I) complex [Co(IAd)(eta(2)-PhC=CPh)(CH2TMS)] from the reaction of 1 with the acetylene, point out a modified Chalk-Harrod catalytic cycle for these hydrosilylation reactions. The high selectivity is thought to be governed by steric factors.