Cucurbiturils as Reaction Containers for Photocycloaddition of Olefins

The [2+2] photocycloaddition (PCA [2+2]) of alkenes is one of the most synthetically useful photoreactions. It is a convenient one-step reaction that is useful for generating substituted cyclobutanes, polymers, and biologically relevant molecules. However, the reaction efficiency is limited by its bimolecular nature requiring encounter between two reactants within the narrow window of excited state lifetime of the photoactive alkene, and competition from the unimolecular photoisomerization. Our groups have utilized macrocyclic cavitands, especially cucurbiturils(CB), to confine two alkene molecules within their cavities and steer them towards a single dimer regio- and stereoselectively. Although, primarily the review focuses on photocycloaddition within CBs, such reactions in closely related cavitands such as cyclodextrins (CD) and calixarenes (CA) are also briefly mentioned to provide a comparison with CBs. Studies on photocycloaddition of olefins within CB by other research groups are also briefly highlighted. A mechanistic model, with ability to predict the nature of the dimer product formed within the above reaction containers is included.     

The Photocycloaddition of Olefins to Unsaturated 3-Ketosteroids

Photoadditions of ethylene and of cyclopentene to Δ⁴ - and Δ^4,6-3-ketosteroids gave mixtures of cis -4α,5α and trans -4α. 5β adducts. In the case of cyclopentene and Δ^4,6-androstadiene-3-one-17β-ol propionate, only the trans adduct was observed. Cis -4β,5β adducts were obtained by base-catalyzed isomerization of the trans adducts. The ratio of cis:trans adducts varied considerably with solvent, temperature, and olefin concentration in steroid reactions but not in reactions with cyclohexenone. The different types of adducts exhibited markedly different ORD curves in agreement with the structures assigned. Carbonyl maxima of trans adducts appeared at shorter wavelengths than maxima of cis adducts in both infrared and ultraviolet spectra. The infrared shifts provide a convenient method for differentiating between cis and trans fused isomers.     

Silver Hexafluoroantimonate‐Catalyzed Three‐Component [2+2+1] Cycloadditions of Allenoates,Dual Activated Olefins,and Isocyanides

The intermolecular [2+2+1] multicomponent cycloadditions from readily available allenoates, dual activated olefins and isocyanides catalyzed by silver hexafluoroantimonate were studied. This protocol allowed the syntheses of highly functionalized five‐membered carbocycles with exclusive regioselectivity and stereoselectivity in an efficient and atom‐economical manner.     

四氮杂杯[2]芳烃[2]三嗪叠氮化衍生物的合成及其与RDX的配合研究

文合成了氮原子桥连杯[2]芳烃[2]三嗪化合物。室温下,以碳酸钾为缚酸剂,利用三聚氯氰和间苯二胺的亲核取代反应合成主体,并将其叠氮化,反应温度为40％。产物通过元素分析,红外光谱和氢谱对其结构进行了表征,并采用XRD对氮杂杯[4]芳烃及其衍生物与黑索今的配合性能进行了表征分析,结果表明主客体之间发生了相互作用。     

对叔丁基杯[6]甲酯芳烃萃取Sr~(2+)的特性研究

根据高放废液中Sr~(2+)的萃取分离需求,合成了对叔丁基杯[6]甲酯芳烃(Calix SMO),并利用FT-IR、1H-NMR和MS表征确认了其化学结构。选择CH2Cl2作为Calix SMO的稀释剂,当体系初始HNO3浓度为3 mol×L-1时,在298 K下,萃取时间120 min,对Sr~(2+)的萃取率为60%;通过计算,有机相中Calix SMO与Sr~(2+)包合比为1:2。分别研究对K+、Sb3+、Ca~(2+)、Sm3+、Sn4+、Na+的萃取,表明Calix SMO对Sr~(2+)有良好的选择性。     

Genetic Encoding of a Bioconjugation Handle for [2+2+2] Cycloaddition Reactions

Protein bioconjugates have many critical applications, especially in the development of therapeutics. Consequently, the design of novel methodologies to prepare protein bioconjugates is of great importance. Herein we present the development and optimization of a novel strategy to prepare bioconjugates through a genetically encoded [2+2+2] cycloaddition reaction. To do this, a novel unnatural amino acid (UAA) containing a dipropargyl amine functionality was synthesized and incorporated site specifically. This UAA-containing protein was reacted with an alkyne-containing fluorophore to afford a covalently linked, well-defined protein bioconjugate. This reaction is convenient with an optimized reaction time of just two hours at room temperature and yields a stable, polysubstituted benzene ring. Overall, this work contributes a new bioconjugation strategy to the growing toolbox of reactions to develop protein bioconjugates, which have a myriad of applications.     

[60]富勒烯[2+1]环加成反应研究进展

对[60]富勒烯的[2 1]环加成反应、主要试剂及反应机理进行了综述。     

联烯类化合物[3+2]环加成反应的研究进展

环加成反应是有机化学中非常重要的一类反应,常用于多元环类化合物的合成。联烯是具有丙二烯结构单元的一类不饱和化合物,广泛存在于自然界中,由于其特殊结构与反应活性,可与许多含不饱和键的化合物发生环加成反应来制备吲哚、呋喃或吡啶等多种环状化合物。近年来,联烯及其衍生物已经引起了国内外许多科研工作者的兴趣。综述了近几年联烯类化合物与含各种不饱和键化合物[3+2]环加成反应的研究进展,并对其发展方向进行了展望。     

Hydrogen-Bonding Organocatalysis Enabled Photocatalytic Intramolecular [2+2]-Cycloaddition Reaction

The combination of organocatalytic activation and photocatalysis for enabling the intramolecular [2+2]-cycloaddition of enone-ene substrates bearing one Lewis base binding site is reported. While in a variety of solvents a poor conversion or no reaction takes place in the absence of a hydrogen bonding catalyst, the corresponding ring-fused cyclobutane products could be built in moderate to good yields using a synergistic dual iridium-urea co-catalytic system. Control and mechanistic studies supported the postulated interaction between the organocatalyst and the substrate, which proved essential for an efficient energy transfer from the photosensitizer.     

二维纳米发光材料[CdxMg6-xAl2(OH)16]2+[S2-·4H2O]2-:Eu3+发光性质的研究

报道了稀土离子Eu3+的含量对二维纳米发光材料[CdxMg6-xAl2(OH)16]2+[S2-@4H2O]2-发光强度的影响,并对基质中Cd2+离子的含量、硫化时间、灼烧温度等合成条件对发光材料发光强度的影响进行了研究.     

Thiourea-catalyzed dearomatizing [4+2] cycloadditions of 3-nitroindole

We have developed two efficient thiourea promoted dearomatizing processes involving the cycloadditions of 3-nitroindoles. The C2C3 double bond of the heteroarene can be involved as electron-poor 2π dienophile in [4+2] cycloadditions. While the uncatalyzed process requires harsh conditions, the organocatalyzed reaction takes place at room temperature and atmospheric pressure. The C2C3NO motif of the heteroarene can also react as an electron-poor 4π heterodiene in [4+2] / [3+2] cycloadditions cascades, under high pressure. In contrast to Lewis acid activation, thiourea promotion thus proves efficient even under unconventional activation conditions and in the presence of acid sensitive reactants such as enol ethers.     

Mg(II)-Catalyzed [4+2] Annulation for the Synthesis of 2-Arylquinoline Motifs: Applications and DFT Studies

Mg-catalyzed [4+2] cycloaddition reactions between 2-aminobenzaldehydes and ynones offered an array of 2-arylquinoline motifs merged with a CF₃-acyl group. Furthermore, with Mg-catalyzed [4+2] annulation as the key step, DDD107498, DDD102542, and Hit analogues were assembled. Finally, a computational study of the reaction mechanism was conducted.     

[3+2]-Cycloadditions of nitrilimines with heteroaryl thioketones

The in situ generated nitrilimines are trapped efficiently with heteroaryl thioketones bearing thiophen-2-yl or selenophen-2-yl substituents. The exclusive products observed in these reactions are 2,3-dihydro-1,3,4-thiadiazoles formed via regioselective [3+2]-cycloaddition. Competitive head-to-tail dimerization of the intermediate 1,3-dipoles was not observed in any of the studied reactions.     

混合C_8烯烃氢甲酰化反应的实验研究

对几种铑膦络合物催化混合 C8烯烃氢甲酰化反应作了实验研究 ,结果表明 ,在一定反应条件下 ,[Rh( CH3COO) 2 ]2 、Rh( CO) PPh3( acac)和 Rh6 ( CO) 16 均是有效的催化剂前体。配体、铑的浓度及溶剂对催化体系性能影响的实验证明 ,外加 OPPh3、选用适量 Rh浓度及加入二乙二醇二甲醚或四乙二醇二甲醚等溶剂对 C8烯烃氢甲酰化反应生成 C9醛是有利的。实验表明 ,对于 [Rh( CH3COO) 2 ]2 - OPPh3催化体系在 1 40℃及 1 0 .5MPa反应条件下 ,混合 C8烯烃氢甲酰化反应生成 C9醛的收率可达 90 %以上。     

邻菲咯啉衍生物钌配合物的制备及性能研究

钌-邻菲咯啉配合物已经广泛应用于电化学、光化学领域,以羟基苯基并[4,5]-邻菲咯啉（Hpip）为配体,合成二氯化三羟基苯基并[4,5]-邻菲咯啉钌（Ru（Hpip）3Cl2）。应用红外、紫外和荧光光谱对产物进行表征,用循环伏安法考察其电化学行为,研究pH、氧对其荧光强度的影响。结果表明Ru（Hpip）3Cl2在玻碳电极上有准可逆的电化学行为,在溶液中其对氧的响应倍数（I0／I）高达11．9。