1,3-Dipolar Cycloaddition of Polycyclic Aromatic Azomethine Ylides and Alkynylbenziodoxoles for Synthesis of Functional Dibenzoullazines

A new family of dibenzoullazine derivatives was synthesized through 1,3-dipolar cycloaddition of polycyclic aromatic azomethine ylides with alkynylbenziodoxoles followed by oxidation.The benziodoxole moiety in the resulting products was used as a versatile linchpin for the synthesis of structurally diverse functional dibenzoullazines that are difficult to access by other synthetic methods.

Synergistic Catalysis with Azomethine Ylides

Azomethine ylides are useful intermediates for the rapid construction of chiral N-containing compounds.However,its synthetic potential has not been fully developed due to the limited reaction models.In combination with synergistic catalysis and azomethine ylide chemistry,we have developed several types of novel catalytic system including Cu/Pd,Cu/Ir and PTC/Ir catalysis;which can convert readily-available azomethine ylides to various high-valued molecules such as unnatural a-amino acids,homoallylic amines and N-heterocycles.Compared with the traditional mono-catalysis,the synergistic catalyst system exhibits enhanced catalytic efficiency and chiral induction ability in many cases.In addition,we have demonstrated that these strategies could be applied in the construction of bioactive compounds and natural products.

Cu-catalyzed endo-selective asymmetric 1,3-dipolar cycloaddition of azomethine ylides with ethenesulfonyl fluorides: Efficient access to chiral pyrrolidine-3-sulfonyl fluorides

Cu-catalyzed endo-selective asymmetric 1,3-dipolar cycloaddition of azomethine ylides with ethenesulfonyl fluorides(ESFs) was successfully developed, this protocol provided an efficient and facile method to a wide range of chiral pyrrolidine-3-sulfonyl fluorides with good to excellent results(up to 87% yield,>20:1 dr, 94% ee). Some other chiral sulfonyl derivatives, such as sulfonamide and sulfonate, were easily accessible through simple transformations with high yields, which demonstrated that the cycloaddition products could be synthetically useful in the sulfur(VI) fluoride exchange(Su FEx) chemistry.

A Facile Access to Fluorinated Pyrrolidines via Catalytic Asymmetric 1,3-Dipolar Cycloaddition of Azomethine Ylides with Methyl a-Fluoroacrylate

Asymmetric 1,3-dipolar cycloaddition of methyl a-fluoroacrylate with azomethine ylides for the construction of optically active fluorinated pyrrolidines bearing one unique fluorinated quaternary and two tertiary stereogenic cen- ters has been achieved with Cu（CH3CN）4BF4/TF-BiphamPhos complexes for the first time. This catalytic system performs well over a broad scope of substrates, providing the synthetically useful adducts in good yields and excel- lent diastereoselectivities and good to high enantioselectivities.

Synthesis and Crystal Structure of 1-Ethyl 3-Methyl 6-Benzyl-2-methyl-5-oxo-5,6-dihydropyrrolo[1,2-c]quinazoline-1,3-dicarboxylate

The crystal structure of the title compound（C24H22N2O5, Mr = 418.44） has been determined by single-crystal X-ray diffraction. The crystal is of orthorhombic, space group P21/c with a = 7.751（2）, b = 12.392（4）, c = 21.326（6）, V = 2048.4（1）3, Z = 4, Dc = 1.357 g/cm3, F（000） = 880, μ（MoKα） = 0.096 mm-1, the final R = 0.0731 and wR = 0.1982 for 3335 observed reflections（I 〉 2σ（I））. Intermolecular C（24）–H（24B）···O（1） hydrogen bond is observed in the structure.

Synthesis and Crystal Structure of 3′-Ethyl 5′-Methyl 1-Benzyl-4′-methyl-2-oxo-3′,4′-dihydrospiro-[indoline-3,2′-pyrrole]-3′,5′-dicarboxylate

The crystal structure of the title compound（C24H24N2O5, Mr = 420.45） has been determined by single-crystal X-ray diffraction. The crystal is of triclinic, space group P1 with a = 8.991（1）, b = 11.166（1）, c = 11.169（1） , α = 91.413（2）, β = 105.887（2）, γ = 90.992（2）°, V = 1077.8（2） 3, Z = 2, Dc = 1.296 g/cm^3, F（000） = 444, μ（MoKα） = 0.091 mm^-1, the final R = 0.0466 and wR = 0.1507 for 4185 observed reflections（I 〉 2σ（I））. The single-crystal X-ray diffraction data indicated intermolecular C（17）–H（17）O（4）, C（5）–H（5）… O（4） hydrogen bonds and C–H…π interaction in the structure.

Synthesis of Novel Spiro Thiazolo[3,2-a][1,3,5]triazines via 1,3-Dipolar Cycloaddition of Azomethine Ylide

The 1,3-dipolar cycloaddition of an azomethine ylide generated by a decarboxylative route from sarcosine and acenaphthenequinone to 7-arylmethylidene-3-aryl-3,4-dihydro-2H-thiazolo[3,2-aJ[1,3,5]triazin-6（7H）-ones afforded novel dispiro[acenaphthylene-1,2’-pyrrolidine]-3＇,7″-[1,3]thiazolo[3,2-a][1,3,5]triazines in moderate yields. The structures of the products were determined and characterized thoroughly by NMR, MS, IR, elemental analysis and X-ray crystallographic analysis. The results of experiment indicated that this 1,3-dipolar cycloaddition proceeded with high stereoselectivity and regioselectivity.

Pyridine-Fused Azacorannulene:Fine-Tuning of the Structure and Properties of Nitrogen-Embedded Buckybowls

Heteroatom-embedded buckybowl molecules provide a fundamental molecular framework that has potential applications in various research fields.However,selective introduction of heteroatoms into buckybowls is challenging,and thus,studies investigating the effect of introduced heteroatoms have been limited.Here,we report the synthesis of pyridine-fused azacorannulene molecules.The influence of nitrogen atoms introduced into the peripheral positions on the structural,electronic,and optical properties is discussed.

Highly stereoselective construction of polycyclic benzofused tropane scaffolds and their latent bioactivities: bifunctional phosphonium salt-enabled cyclodearomatization process

Structurally fused heterocycles encompassing a centerpiece of benzotropane are significant scaffolds with a plethora of promising biological activities,but such molecular architectures pose a long-standing daunting synthetic challenge.Herein,we reported a highly efficient asymmetric cyclodearomatization of 2-nitrobenzofurans with cyclic azomethine ylides by employing bifunctional phosphonium salts as phase-transfer catalysts.Under optimized reaction conditions,a diverse array of polycyclic benzofused tropane derivatives with four contiguous 4°/3°stereocenters were readily synthesized in both high yields and diastereoselectivities with up to>99%ee.The practicality and utility of this protocol were further demonstrated by the scaled-up reaction and facile elaborations.Moreover,preliminary investigations into their antitumor activities were also presented.

1,3-Dipolar cycloaddition reaction for diastereoselective synthesis of functionalized dihydrospiro[indoline-3,2'-pyrroles]

The BF_3OEt_2 catalyzed one-pot 1,3-dipolar cycloaddition reaction of benzylamines,isatins and dimethyl acetylenedicarboxylate in dry methylene dichloride afforded the functionalized dihydrospiro[indoline-3,2＇-pyrroles]in moderate to good yields and with high diastereoselectivity.The reaction was accomplished by the tandem 1,3-dioplar cycloaddition of in situ generated azomethine ylide with acetylenedicarboxylate and the nucleophilic addition of pyrrole ring to second molecular acetylenedicarboxylate.

1,3-Dipolar cycloaddition for selective synthesis of functionalized spiro[indoline-3,3’-pyrrolizines]

The 1,3-dipolar cycloaddition reaction of dimethyl hex-2-en-4-ynedioate with azomethine ylides derived from reaction of L-proline with various isatins in methanol selectively resulted in the formation of functionalized spiro[indoline-3,3’-pyrrolizine]acrylates as main products and spiro[indoline-3,3’-pyrrolizine]propiolates as minor products.This result indicated that the electron-deficient alkyne has higher reactivity than that of electron-deficient alkene in 1,3-dipolar cycloaddition reaction.