New synthetic methodology for 3-aminotropones

A new synthetic methodology for 3-aminotropones is described. Tropones and 3-aminotroponic building blocks, present in a number of active natural products, could be prepared by a two step synthetic pathway: a first step consisting in a [4+3] cycloaddition reaction between a conveniently substituted α,α′-dihaloketone and a furan derivative functionalized on C-2 by a protected amino group. The second step is based on a rearrangement of the cycloadduct, via the cleavage of the oxygen bridge, under basic conditions.     

C1-C2 cleavage of C1-functionalized 8-oxabicyclo-[3.2.1]-oct-6-en-3-one. Stereoselective preparation of 4-substituted butenolides

Diastereoisomeric epimers at C1′ of 4-(1-methyl-2-oxo-butyl)-2-butenolide, and the corresponding saturated γ-lactones, were synthesized by hydrolysis of 1-methoxy-8-oxabicyclo[3.2.1] oct-6-en-3-one, under acidic conditions. These butenolides are interesting synthetic building blocks, precursors of biologically active natural products like insect pheromones. Their formation could be explained by a cleavage at the C1-C2 bond of the oxabicyclic precursor. On the basis of the experimental data we have proposed a mechanism of hydrolytic cleavage which is formally an intramolecular reverse Dieckmann process.     

Reaction of ene-bis(phosphinylallenes): [2+2] versus [4+2] cycloaddition

Reaction of ene-bis(phosphinylallenes), derived from ene-bis(propargyl alcohols) and chlorodiphenylphosphine, was investigated. Benzene-bridged bis(phosphinylallenes) exclusively gave intramolecular [2+2] cycloadducts in the presence of dimethyl fumarate in sharp contrast to the reaction of benzene-bridged bis(sulfinylallenes), which gave the corresponding [4+2] cycloadducts. On the other hand, substituted ethylene- or five-membered heterocycle-bridged bis(phosphinylallenes) provided [4+2] cycloadducts. Reaction of benzene-bridged diallene bearing both a sulfinyl group and a phosphinyl group on the two allenyl groups was also described.     

Synthesis of 8-substituted bicyclo[3.2.1]octane-6-carboxylic acids and anti-convulsant properties of the corresponding amides

Novel 8-substituted bicyclo[3.2.1]octane-6-carboxylic acids have been made via [3+2]cycloaddition to alkyne 2. A number of the corresponding amides are anti-convulsant in mice.     

Efficient and Selective Extraction of Fe3+ by Mono- and Di-Azocalix[4]arene Derivatives

Nine series of chromogenic mono- (A1-A2) and di- (B1-B7) substituted azocalix[4] arene analogues containing more than one azo group were described. Different chelating agents like ester and ketone moieties were grafted on the lower rim position of azocalix[4]arenes. The selective extraction properties of Fe³⁺ cation were studied by liquid-liquid extraction. This extraction process was carried out by using compounds A1-A2 and B1-B7. The results proved that coupling of phenylazo groups onto the upper rim of azocalix[4]arenes yielded greater efficiency and selectivity for carrying the Fe³⁺ cation in the extraction process at pH 2.2.     

[Hg3]4+ Cation in Inorganic Crystal Structures

The crystal-chemical structure of the minerals and inorganic compounds kuznetsovite [Hg₃](AsO₄)Cl and terlinguaite [Hg₃][HgO₂]Cl₂, as well as [Hg₃]₃(AsO₄)₄ and [Hg₃]₂[HgO₂](PO₂ and their analogs, is considered from the viewpoint of the packing of large supramolecular atomic groups. The cationic layer of polyhedra around the large [Hg₃]⁴⁺ cations, alternating with the anionic layer of [HgO₂]^2-, (AsO₄)^3-, (PO₄)^3-, Cl^-, plays the major role in structure formation. Segregation of mercury cations of different valences possibly reflects the solid-state transformations occurring in nature and accompanied by mercury liberation.     

A novel synthesis of bicyclo[3.3.0]oct-1-en-3-ones from cyclobutanones through [chloro(p-tolylsulfinyl)methylidene]cyclobutanes with ring expansion

Treatment of [chloro(p-tolylsulfinyl)methylidene]cyclobutanes, which were synthesized from cyclobutanones and chloromethyl p-tolyl sulfoxide in three steps in high overall yields, with excess cyanomethyllithium gave enaminonitriles in high yields. Heating of these enaminonitriles with H₃PO₄ in acetic acid gave 2-cyanobicyclo[3.3.0]oct-1-en-3-ones in good yield. On the other hand, treatment of the [chloro(p-tolylsulfinyl)methylidene]cyclobutanes with cyanomethyllithium followed by lithium carbanion of the homologues of acetonitrile afforded enaminonitriles having a substituent at the 3-position. Heating of the enaminonitriles with H₃PO₄ in acetic acid gave 2-substituted bicyclo[3.3.0]oct-1-en-3-ones in good to high yields. This method offers a novel and versatile procedure for synthesis of 2-substituted bicyclo[3.3.0]oct-1-en-3-ones from cyclobutanones in good overall yields.     

单取代罗丹明-硫杂杯[4]芳烃衍生物的合成及对Fe~(3+)离子的荧光探针性质研究

以1,3-交替-二羧基甲氧基硫杂杯[4]芳烃为原料,通过与罗丹明乙二胺衍生物的酰化反应得到罗丹明基团单取代的硫杂杯[4]芳烃衍生物。目标化合物结构经IR,NMR,MS及元素分析等技术表征。荧光及可见吸收光谱法研究表明化合物对Fe3+具有探针性质,在乙醇-水(1/1,V/V)Tris-HCl(pH=6.0)缓冲溶液中,对Fe3+呈现光关-开响应,并观察到显著的荧光增强和颜色变红现象。测定了Fe3+-配合物的组成、稳定常数及荧光量子产率。     

A method for synthesis of bicyclo[3.3.0]oct-1-en-3-ones from cyclobutanones with one-carbon ring expansion and its application to a formal synthesis of racemic 1-desoxyhypnophilin

A method for synthesis of 2-cyanobicyclo[3.3.0]oct-1-en-3-ones and 2-substituted bicyclo[3.3.0]oct-1-en-3-ones was developed by assembly of three components, cyclobutanones, chloromethyl p-tolyl sulfoxide, and nitriles, with one-carbon ring expansion of the cyclobutane ring. As an application of this method, a formal synthesis of 1-desoxyhypnophilin in racemic form was performed starting from 3,3-di(phenylthiomethyl)cyclobutanone.     

由N-苯基[1,3]苯并噁嗪正离子与烯烃[4+2]反应合成喹啉并[1,2-c][1,3]苯并噁嗪-6-酮衍生物

以BF3·OEt2 为催化剂, 在室温下通过4-羟基-N-苯基[1,3]苯并噁嗪-2-酮的脱羟基产生N-苯基[1,3]苯并噁嗪正离子, 然后与富电子烯烃发生Diels-Alder反应, 合成出了一系列喹啉并[1,2-c][1,3]苯并噁嗪-6-酮和喹啉并[1,2-c][1,3]萘并噁嗪-6-酮衍生物.     

Synthesis of functionalized azacalix[3]aromatics from azacalix[4]pyrimidine: unexpected macrocyclic transannular reactions

The lower-rim formylated azacalix[4]pyrimidine underwent transannular Friedel–Crafts and dehydrogenative cross coupling reactions to afford, respectively, 2,4,5,7-tetraaza-9,10-dihydroacridine and -dihydroacridin-9-one containing azacalix[3]aromatics. Dihalogenation of the later compound produced resolvable inherently chiral azacalix[3]aromatics.     

Concise [4+3] cycloaddition reaction of pyrroles leading to tropinone derivatives

A concise [4+3] cycloaddition reaction of pyrroles with 2-(silyloxy)allyl cations has been developed. The oxyallyl cations stabilized with a methylthio group or geminal methyl groups were generated from the corresponding allylic alcohols under the influence of a Brönsted acid (Tf₂NH), respectively. The use of N-nosyl-protected pyrroles as the four-carbon unit was found to give tropinone derivatives in high yield.     

Synthesis of conformationally restricted nicotine analogues by intramolecular [3+2] cycloaddition

We describe the synthesis of a series of conformationally constrained nicotine analogues 2-5 from appropriate pyridine-containing enals, featuring an intramolecular azomethine ylide-alkene [3+2] cycloaddition. The objective of the current project is to develop new selective nAChRs-targeting ligands. Of the nicotine analogues that we have studied, the conformation-restricting ring B unit can be either a five-membered carbocycle, or a six-membered carbocycle or heterocycle. The present work constitutes a general method for rapid assembly of other related tricyclic nicotine analogues.     

超分子自组装合成杯[4]芳烃黄原酸镍(Ⅱ)配合物

利用二维和三维的大环及笼状主体分子与金属离子直接进行自组装反应合成新型有机无机杂化分子是当前超分子领域的研究热点之一。这类分子不仅具有新奇的光、电、磁等特性，而且还可作为新型的主体分子在客体识别、催化、吸附与分离等方面有广阔的应用前景。杯芳烃是有机超分子领域广受     

Palladium-Catalyzed Asymmetric [4+3] Cyclization of Trimethylenemethane: Regio-, Diastereo-, and Enantioselective Construction of Benzofuro[3,2-b]azepine Skeletons

The palladium-catalyzed asymmetric [4+3] cyclization of trimethylenemethane donors with benzofuran-derived azadienes furnishes chiral benzofuro[3,2-b]azepine frameworks in high yields (up to 98 %) with exclusive regioselectivities and excellent stereoselectivities (up to >20:1 d.r., >99 % ee). This catalytic asymmetric [4+3] cyclization of Pd-trimethylenemethane can enrich the arsenal of Pd-TMM reactions in organic synthesis. In addition, this strategy provides an alternative approach to chiral azepines by a transition-metal-catalyzed asymmetric [4+3] cyclization.     

Recyclable gallium(III) triflate-catalyzed [4+3] cycloaddition for synthesis of 2,4-disubstituted-3H-benzo[b][1,4]diazepines

Simple and efficient Ga(OTf)₃-catalyzed [4+3] cycloaddition of 1,3-diarylpropynones and o-phenylenediamines is developed for the preparation of 2,4-disubstituted-3H-benzo[b][1,4]diazepines. The reaction has advantages of using a green solvent, generating a minimal amount of waste, and easy catalyst recycle.     

Synthesis of nitrogen bicyclic scaffolds: pyrimido[1,2-a]pyrimidine-2,6-diones

The multi-step synthesis of 1,3,7-trisubstituted pyrimido[1,2-a]pyrimidinediones starting from isothiocyanates is described. These nitrogen bicycles were prepared by an iterative sequence of functionalization/cyclocondensation reactions. [4+2] Cycloaddition reactions took place between diazadienic chains and various acyl chlorides providing sophisticated heterobicycles.     

Synthesis and Crystal Structure of 5-Amino-4-cyano-8-isobutyl-7-isopropyl-6-thiocarbamoyl-2-azabicyclo[2.2.2]oct-5-en-3-thione

5-Amino-4-cyano-8-isobutyl-7-isopropyl-6-thiocarbamoyl-2-azabicyclo[2.2.2]oct-5-en-3-thione was synthesized by the condensation of isovaleryl aldehyde with cyanothioacetamide. The structure of the product was established by X-ray crystallography.     

[6+3] Cycloaddition of fulvenes with 3-oxidopyrylium betaine: a novel methodology for the synthesis of fused cyclooctanoid natural products

Fulvenes undergo an easy [6+3] cycloaddition with 3-oxidopyrylium betaines leading to 5-8 fused oxabridged cyclooctanoids.     

Formal [4 + 4] cycloaddition of 3-arylcyclobutanones with anthracene and their acid-promoted intramolecular cyclization with skeletal rearrangement

A reaction of 3-arylcyclobutanones with anthracene in the presence of TiCl₄ gave 14-aryl-9,10-dihydro-9,10-butanoanthracen-12-ones as a formal [4 + 4] cycloadduct of anthracenes with a C4 unit formed by cleaving the more substituted C2C3 bond of cyclobutanones. On the other hand, activation of 3-arylcyclobutanones with TfOH in the absence of nucleophiles gave 2-tetralones with skeletal rearrangement.