Oxidative (3+3) Cycloaddition/Ring-Opening Reactions of Simple Urea Derivatives and N,N'-Cyclic Azomethine Imines to Construct 1,2,3,5-Tetrazine-4(1H)-one Derivatives.

A novel oxidative (3 + 3) cycloaddition/ring-opening reaction of N,N'-cyclic azomethine imines with the in situ generated diaza-oxylallyl cations from simple urea derivatives in the presence of base and PhI(OAc)2 has been developed. This transformation performs well over a broad substrate scope, which provides facile and rapid access to 1,2,3,5-tetrazine-4(1H)-one derivatives in good yields.

Base-Mediated Tandem [3 + 2] Cycloaddition/Ring Openning Reaction of Arylhydrazonoyl Chlorides with Arylnitroso Compounds for Synthesis of Substituted Diazene Oxides.

A base-mediated tandem [3 + 2] cycloaddition/ring opening reaction of nitrilimines generated from arylhydrazonoyl chlorides with arylnitroso compounds has been developed. This protocol provides a novel and rapid approach for the synthesis of substituted azoxy compounds under mild conditions with moderate to good yields and a broad substrate scope.

Iridium-Catalyzed Intramolecular Asymmetric Allylation of Vinyl Benzoxazinones for the Synthesis of Chiral 4H-3,1-Benzoxazines via Kinetic Resolution.

Chiral benzoxazinones and 4H-3,1-benzoxazines as important motifs are widely found in abundant pharmaceuticals and biological molecules. We herein successfully developed the first kinetic resolution (KR) process of racemic benzoxazinones through Ir-catalyzed asymmetric intramolecular allylation, furnishing a wide range of chiral benzoxazinones and 4H-3,1-benzoxazines with excellent results via outstanding KR performances (with the s factor up to 170). This protocol exhibited broad substrate scope generality and good functional group tolerance, and the chiral 4H-3,1-benzoxazine products could be readily transformed to other useful optically active heterocycles.

Stereoselective construction of spiro(butyrolactonepyrrolidines) by highly efficient copper(I)/TF-BiphamPhos-catalyzed asymmetric 1,3-dipolar cycloaddition.

Pyrrole into one: The catalytic asymmetric 1,3-dipolar cycloaddition of cyclic aldimino esters has been accomplished for the first time, enabling facile access to spiro(butyrolactonepyrrolidines) containing one spiro quaternary center and three tertiary stereogenic centers (see scheme). The catalytic system performs well with a broad range of substrates, furnishing synthetically useful adducts in high yields, with excellent diastereo- and enantioselectivities under mild conditions.

Ag(I)-catalyzed tandem [6+3] annulation/isomerization of isocyanoacetates with fulvenes: an expedient approach to synthesize fused dihydropyridines.

An unprecedented Ag(i)-catalyzed tandem [6+3] cycloaddition/isomerization of isocyanoacetates with fulvenes has been developed, affording the fused dihydropyridine derivatives in good yields with exclusive regioselectivities.

Silver(I)-Catalyzed Enantioselective Desymmetrization of Cyclopentenediones: Access to Highly Functionalized Bicyclic Pyrrolidines.

A highly enantioselective desymmetrization of prochiral cyclopentenediones via Ag(I)-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylide has been developed successfully. The methodology performs well over a broad scope of substrates, which provides facile access to a series of highly functionalized bicyclic pyrrolidine/cyclopentane derivatives in good to high yields with excellent stereoselectivities.

Exoselective 1,3-dipolar [3 + 6] cycloaddition of azomethine ylides with 2-acylcycloheptatrienes: stereoselectivity and mechanistic insight.

A highly exo-selective 1,3-dipolar [3 + 6] cycloaddition of azomethine ylides with 2-acylcycloheptatrienes was realized with a Cu(I)/(S,R(p))-PPF-NHMe complex as the catalyst, leading to a diverse range of bridged piperidines with multiple functionalities in good yield with excellent stereoselectivity control. Theoretical calculations indicated a stepwise mechanism for this exo-selective [3 + 6] annulation, which accounts for the remarkable feature of this annulation: all of the larger substituent groups occupy the axial positions in the six-membered chairlike conformation of the piperidine ring.

Highly efficient construction of spirocyclic chromanone-pyrrolidines via Cu(I)/TF-BiphamPhos-catalyzed asymmetric 1,3-dipolar cycloaddition.

A facile synthesis of highly functional spiro-[4-chromanone-3,3'-pyrrolidine] bearing one unique spiro quarternary and three tertiary stereogenic centers is developed in excellent stereoselectivity for the first time.

Stereoselective construction of a 5-aza-spiro[2,4]heptane motif via catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides and ethyl cyclopropylidene acetate.

A direct and facile synthesis of highly functional 5-aza-spiro[2,4]heptanes, a valuable structural motif for drug discovery, is developed via catalytic asymmetric 1,3-dipolar cycloaddition of cyclopropylidene acetate and azomethine ylides for the first time.