Xin-Yuan Liu

Metal-Free Direct Intramolecular Carbotrifluoromethylation of Alkenes to Functionalized Trifluoromethyl Azaheterocycles

The first example of a metal-free direct carbotrifluoromethylation of alkenes using inexpensive TMSCF3 as the CF3 source is described. The methodology not only exhibits high chemoselectivity for this transformation but also expands the substrate scope that is difficult to access by known transition-metal-catalyzed methods.

In situ generation of electrophilic trifluoromethylthio reagents for enantioselective trifluoromethylthiolation of oxindoles.

An organocatalytic asymmetric trifluoromethylthiolation reaction via in situ generation of active electrophilic trifluoromethylthio species involving trichloroisocyanuric acid and AgSCF3 as a practical and easily handled electrophilic SCF3 source for CSP(3)-SCF3 bond formation was developed. Reactions with this one-pot version strategy occurred in good yields and excellent stereoselectivities to access enantiopure oxindoles bearing a SCF3-substituted quaternary chiral center. The straightforward process described here makes use of simple starting materials and proceeds under mild conditions, which will be useful in medicinal chemistry and diversity-oriented syntheses.

Enantioselective CH Bond Functionalization Triggered by Radical Trifluoromethylation of Unactivated Alkene

An asymmetric unactivated alkene/C-H bond difunctionalization reaction for the concomitant construction of C-CF3 and C-O bonds was realized by using a Cu/Brønsted acid cooperative catalytic system, thus providing facile access to valuable chiral CF3-containing N,O-aminals with excellent regio-, chemo-, and enantioselectivity. Mechanistic studies revealed that this reaction may proceed by an unprecedented 1,5-hydride shift involving activation of unactivated alkenes and a radical trifluoromethylation to initiate subsequent enantioselective functionalization of C-H bonds. Control experiments also suggested that chiral Brønsted acid plays multiple roles and not only controls the stereoselectivity but also increases the reaction rate through activation of Tognis reagent.

Efficient Copper-Catalyzed Direct Intramolecular Aminotrifluoromethylation of Unactivated Alkenes with Diverse Nitrogen-Based Nucleophiles

A mild, convenient, and step-economical intramolecular aminotrifluoromethylation of unactivated alkenes with a variety of electronically distinct, nitrogen-based nucleophiles in the presence of a simple copper salt catalyst, in the absence of extra ligands, is described. Many different nitrogen-based nucleophiles (e.g., basic primary aliphatic and aromatic amines, sulfonamides, carbamates, and ureas) can be employed in this new aminotrifluoromethylation reaction. The aminotrifluoromethylation process allows straightforward access to diversely substituted CF3-containing pyrrolidines or indolines, in good to excellent yields, through a direct difunctionalization strategy from the respective acyclic starting materials. Mechanistic studies were conducted and a plausible mechanism was proposed.

Direct Access to α-Trifluoromethyl Enones via Efficient Copper-Catalyzed Trifluoromethylation of Meyer–Schuster Rearrangement

A novel domino copper-catalyzed trifluoromethylated Meyer-Schuster rearrangement reaction with Tognis reagent was developed, leading to α-trifluormethyl (CF3) enone products with moderate to good yields. Furthermore, α-CF3 enones can be transformed toward important trifluoromethyl heterocyclic motifs in a one-pot version.

Atroposelective Synthesis of Axially Chiral Biaryldiols via Organocatalytic Arylation of 2-Naphthols

The first phosphoric acid-catalyzed asymmetric direct arylative reactions of 2-naphthols with quinone derivatives have been developed, providing efficient access to a class of axially chiral biaryldiols in good yields with excellent enantioselectivities under mild reaction conditions. This approach is a highly convergent and functional group tolerant route to the rapid construction of axially chiral compounds from simple, readily available starting materials. The excellent stereocontrol of the process stems from efficient transfer of stereochemical information from the chiral phosphoric acid into the axis chirality of the biaryldiol products. Preliminary results demonstrate that the biaryldiols can act as efficient chiral ligands in asymmetric transformations.

Phosphine-Catalyzed Remote β-CH Functionalization of Amines Triggered by Trifluoromethylation of Alkenes: One-Pot Synthesis of Bistrifluoromethylated Enamides and Oxazoles†

An unprecedented phosphine-catalyzed remote β-CH functionalization of amine derivatives triggered by trifluoromethylation of an alkene with Tognis reagent was disclosed. This reaction proceeded through the highly selective and concomitant activation of an unactivated alkene and the β-C sp 3H bond of an amine derivative, providing bistrifluoromethylated enamides in excellent yields with good regio-, chemo-, and stereoselectivity. Furthermore, the newly developed one-pot protocol provides a facile and step-economical access to valuable trisubstituted 5-(trifluoromethyl)oxazoles. Mechanistic studies showed that this reaction may initiate with a novel phosphine-catalyzed radical trifluoromethylation of unactivated alkene via a phosphorus radical cation.

Highly Enantioselective Kinetic Resolution of Axially Chiral BINAM Derivatives Catalyzed by a Brønsted Acid

A highly efficient strategy for the kinetic resolution of axially chiral BINAM derivatives involving a chiral Brønsted acid-catalyzed imine formation and transfer hydrogenation cascade process was developed. The kinetic resolution provides a convenient route to chiral BINAM derivatives in high yields with excellent enantioselectivities.

Alkenyl/Thiol-Derived Metal-Organic Frameworks (MOFs) by Means of Postsynthetic Modification for Effective Mercury Adsorption

The synthesis of new functionally diverse alkenyl-derived Cr-MIL-101s (MIL=material of Institute Lavoisier) was realized by a novel and convenient postsynthetic modification (PSM) protocol by means of the carbon-carbon bond-forming Mizoroki-Heck reaction. The new PSM protocol demonstrates a broad scope of substrates with excellent tolerance of functionality under mild reaction conditions. Moreover, a new metal-organic framework (MOF) that bears both alkenyl and thiol side chains prepared by means of the tandem PSM method has shown excellent adsorbent ability in removing mercury ions from water.

Highly efficient enantioselective three-component synthesis of 2-amino-4H-chromenes catalysed by chiral tertiary amine-thioureas

A three-component cascade reaction of salicylaldehyde, malononitrile/cyanoacetate and nitromethane catalysed by chiral tertiary amino-thioureas was developed, which leads to the production of highly functionalized 2-amino-4H-chromenes in good yields with good to excellent enantioselectivities.