I2-DMSO-Mediated N-H/α-C(sp3)-H Difunctionalization of Tetrahydroisoquinoline: Formal [2 + 2 + 1] Annulation for the Construction of Pyrrolo[2,1-a]isoquinoline Derivatives

An I₂-DMSO-mediated cascade reaction using methyl ketones and 1,2,3,4-tetrahydroisoquinolines (THIQs) as commercially available substrates has been developed for the construction of pyrrolo[2,1-a]isoquinoline derivatives. This metal-free process involves N-H/α-C(sp³)-H difunctionalization of THIQ. Two C-C bonds and one C-N bond are formed in one pot under mild conditions. Besides, a quaternary carbon center has been constructed in this transformation efficiently.

Synthesis of 1-pyrroline derivatives via cyclization of terminal alkynes with 2-azaallyls

An efficient transition-metal-free cyclization reaction to prepare 1-pyrroline derivatives bearing various functional groups is described. In this method, a simple combination of a base and a solvent allows the cyclization reaction of terminal alkynes and 2-azaallyls to be carried out efficiently under mild and metal-free conditions. This cyclization reaction will provide an efficient method for the synthesis of medicinally relevant polysubstituted and multifunctionalized pyrrolines.

Toward a Synthesis of Fawcettimine-Type Lycopodium Alkaloids: Stereocontrolled Synthesis of a Functionalized Azaspirocycle Precursor

The stereocontrolled synthesis of a new azaspirocycle precursor of the fawcettimine-type Lycopodium alkaloids is described. Our approach provides an efficient entry to the azaspirocycle via a cascade Wacker-allylation sequence followed by a highly stereoselective Claisen rearrangement. This azaspirocycle, bearing all of the requisite functionality with pivotal stereogenic centers, is considered to be a versatile precursor useful for the fawcettimine-type Lycopodium alkaloids.

Copper-Catalyzed Synthesis of Substituted Quinazolines from Benzonitriles and 2-Ethynylanilines via Carbon-Carbon Bond Cleavage Using Molecular Oxygen

A copper-catalyzed process for the synthesis of substituted quinazolines from benzonitriles and 2-ethynylanilines using molecular oxygen (O₂) as sole oxidant is described. The mild catalytic system enabled the effective cleavage of the C-C triple bond and construction of new C-N and C-C bonds in one operation. Furthermore, the compound N, N-dimethyl-4-(2-(4-(trifluoromethyl)phenyl)quinazolin-4-yl)aniline (3dj) exhibited obvious aggregation-induced emission phenomenon, and the fluorescence quantum yield (Φ_F,film) and lifetime (τ_film) were measured to be 45.5% and 5.8 ns in thin films state, respectively.

Xanthene-4,5-diamine derivatives: a study of anion-binding catalysis

This study describes the synthesis of a class of anion-binding catalysts based on a xanthene scaffold. Both unsymmetrical catalysts and C₂-symmetrical catalysts were generated, and were examined in the cyclization of 3- and 2-substituted furans onto N-acyliminium ions. Good conversion for each reaction was observed with a variety of anion-binding catalysts (42-76%).

Copper(i)/Lewis acid triggered ring-opening coupling reaction of cyclopropenes with nitriles

A ring-opening coupling reaction of D–A cyclopropenes and nitriles is described for the facile synthesis of γ-amino ketones.

Metal-free [3 + 2 + 1]/[2 + 2 + 1] biscyclization: stereospecific construction with concomitant functionalization of indolizin-5(1H)-one

A metal-free [3 + 2 + 1]/[2 + 2 + 1] biscyclization strategy has been developed for the stereospecific construction with concomitant derivation of biologically significant indolizin-5(1H)-ones from simple and commercial starting materials. The transformations are notable because they can yield five new σ bonds and six stereocenters including a quaternary carbon center in a single operation.