N‐Alkenylated triazolinone ylides were generated through copper‐catalyzed oxy‐N‐alkenylation of triazolopyridines. The mechanistic course of this aerobic tandem reaction has been experimentally elucidated and primary photophysical data of the ylide products are also given.
A multifunctional chiral phosphine‐catalyzed enantioselective [3+2] annulation of Morita–Baylis–Hillman carbonates with barbiturate‐derived alkenes has been achieved under mild conditions, providing a variety of chiral spirobarbiturate‐cyclopentenes in moderate to excellent yields with moderate to excellent diastereo‐ and enantioselectivities.
The first copper(I)‐catalyzed asymmetric 1,3‐dipolar [3+4] cycloaddition of nitrones with azoalkenes has been developed, affording a variety of biologically important 1,2,4,5‐oxatriazepane derivatives in good yields with exclusive regioselectivities and excellent enantioselectivities.
A copper‐catalyzed three‐component (arenes, iodohydrocarbon, and sulfur powder) synthesis of substituted aryl sulfides has been developed. Water is used as the green solvent in a simple and environmentally friendly procedure. Various functional groups attached to the substrates were well tolerated in this process to afford the corresponding products in moderate to good yields.
A Mitsunobu approach for the synthesis of sulfinate esters by direct nucleophilic substitution of alcohols is described. The salient features of this strategy include neutral and metal‐free conditions for the rapid synthesis of sulfinates in high yields. The present protocol using p‐toluenesulfonylmethyl isocyanide (TosMIC) and the triphenylphosphine (TPP)/diisopropyl azodicarboxylate (DIAD) reagent system represents the general synthetic route to this important class of compounds.
A stereocontrolled [4+1] annulation of α‐hydroxycyclobutenones has been disclosed. For the first time, α‐hydroxycyclobutenones have been proven as facile diene precursors for [4+1] annulation. Meanwhile, the reported transformation presents a concise synthetic route to polysubstituted cyclopentenones with high stereoselectivity.
A highly enantioselective one‐pot synthesis of important building blocks, α‐chiral γ‐keto esters, has been developed by combining a quinine‐catalyzed Michael addition of malononitrile to trans‐enones followed by magnesium monoperoxyphthalate (MMPP) oxidation. These synthons proved to be useful reagents for a simple access to challenging cis‐α,γ‐disubstituted γ‐butyrolactones in good diastereoselectivity and high enantiocontrol.
The bis(N‐heterocyclic carbene)(diphenylacetylene)palladium complex [Pd(ITMe)2(PhC≡CPh)] (ITMe=1,3,4,5‐tetramethylimidazol‐2‐ylidene) acts as a highly active pre‐catalyst in the diboration and silaboration of azobenzenes to synthesize a series of novel functionalized hydrazines. The reactions proceed using commercially available diboranes and silaboranes under mild reaction conditions.
A series of trifluoromethyl‐containing heterocycles, like indene and dihydroquinolinone or dihydrocoumarin‐fused tetracyclic compounds have been prepared using copper‐catalyzed cascade reaction of benzene‐tethered 1,7‐enynes. A study of the mechanism indicated that radical trifluoromethylation and sequential 6‐exo‐dig/5‐endo‐trig bicyclization processes were involved in this protocol. Moreover, some selected products showed certain fungicidal activities against 14 kinds of plant fungi which means that these functionalized tetracyclic compounds might be used in the agrochemical field.
The first highly enantioselective intramolecular N−H bond insertion was realized by using copper catalysts modified with chiral spirobisoxazoline ligands, which provides a novel strategy for the synthesis of chiral 2‐carboxytetrahydroquinolines. This reaction features fast reaction rate, high yield, high enantioselectivity, and mild reaction conditions.
A new synthetic method for α‐alkynyl‐α,β‐unsaturated esters is presented herein. The method is based on a copper(I)‐catalyzed three‐component reaction of a terminal alkyne, diazoesters and aldehydes. The reaction is featured by mild conditions, high yields and excellent stereoselectivity. Cu(I) carbene migratory insertion is proposed as the key step in the transformation.
A copper(I)‐catalyzed addition of alkylborane reagents to α‐iminoacetates has been developed to assemble both acyclic and cyclic α‐branched α‐amino carboxylic acid derivatives in good yields. A wide variety of unactivated alkenes are well tolerated in this transformation.
An efficient ligand‐free copper‐manganese (Cu‐Mn) spinel oxide‐catalyzed direct tandem C−H oxygenation and N‐arylation of benzylamines has been developed. The method has been utilized for the synthesis of medicinally important 2‐arylquinazolin‐4(3H)‐ones. Salient features of this method include recyclable catalyst, no ligand, excellent product yields, shorter reaction times and a broad substrate scope.
A novel one‐pot reaction which combines halogenation, decarboxylation/desulfonamidation with oxidation has been developed. Diverse valuable 3,3‐dihalo‐2‐oxindole compounds can be produced rapidly and safely with isolated yields of up to 98% under mild conditions.
2,3‐Dihydroindenes and isoindolines are important skeletons present in medicinal and synthetic chemistry. In this paper, an acetyl bromide promoted metal‐free construction of 2,3‐dihydroindenes and isoindolines with high synthetic efficiency is developed.
A novel and facile iron‐catalyzed tandem annulation of o‐phenylenediamines and diazocarbonyls in water for the construction of polyfunctionalized quinoxalines has been developed. The key strategy includes the one‐pot domino N−H insertion, cyclization, and oxidation reactions. This protocol offers a safe and mild synthetic approach to access a variety of quinoxaline derivatives in high yields. This methodology also allows the formation of biologically interesting pyrazines and benzoquinoxalines.
A facile and efficient potassium hydroxide (KOH)‐catalyzed tandem reaction involving sequential Michael addition of electron‐deficient alkenes with malonic esters, ring opening of activated aziridines and lactamization has been described. A highly functionalized indane‐fused tricyclic scaffold containing three rings, three adjacent stereocenters and a quaternary center was constructed by the formation of two new C–C bonds and one new C–N bond in a diastereoselective manner.
