Gold(III)-catalyzed nucleophilic substitution of propargylic alcohols

Gold-catalyzed nucleophilic substitution on propargylic alcohols, with various C-, O-, and S-nucleophiles, is described under very mild conditions (room temperature, dichloromethane) in 0-97% yield.     

Gold(III)-catalyzed direct nucleophilic substitution of propargylic alcohols

Gold-catalyzed nucleophilic substitution of propargylic alcohols with various nucleophiles (allylsilane, electron-rich aromatics, alcohols, thiols, hydrides, 1,3-dicarbonyl derivatives, sulfonamides) is described under very mild conditions (room temperature in dichloromethane). Preliminary mechanistic investigations suggest a mechanism through a carbocation intermediate. Nucleophilic substitutions on allylic and benzylic alcohols are also described.     

A general and efficient FeCl3-catalyzed nucleophilic substitution of propargylic alcohols

A general and efficient FeCl3-catalyzed substitution reaction of propargylic alcohols with carbon- and heteroatom-centered nucleophiles such as allyl trimethylsilane, alcohols, aromatic compounds, thiols, and amides, leading to the construction of C-C, C-O, C-S and C-N bonds, has been developed.     

Regioselective alkyl and alkynyl substitution reactions of epoxy alcohols by the use of organoaluminum ate complexes: regiochemical reversal of nucleophilic substitution reactions

Unprecedented nucleophilic substitution reactions of 2,3-epoxy-1-alkanols with alkyl- and alkynylaluminum ate complexes have been studied and demonstrated to occur at the C2 position with extremely high stereoselectivity, i.e., with exactly reversed regioselectivity to that obtained in the substitution reactions by normal organoaluminum reagents, resulting in the formation of the C2-alkyl and C2-alkynyl substitution products in excellent yields.     

Abnormal nucleophilic substitution of 3-trichloromethylpyridines by methoxide

3-Trichloromethylpyridine and its α-chlorinated derivatives behave as ambident electrophilic substrates towards methoxide which attacks an α-position and the trichloromethyl group.     

Functionalisation of fluorescent BODIPY dyes by nucleophilic substitution

The BODIPY chromophore can be easily modified by nucleophilic mono- or disubstitution of 3,5-dichloroBODIPY with O-, N-, S- and C-nucleophiles. Absorption and fluorescence spectral data of the new BODIPY derivatives are also reported.     

Synthesis of 4-acylcoumarins by NHC-catalyzed nucleophilic substitution

Coumarins are bioactive; consequently their syntheses are of importance to medicinal chemists. We describe the one-step organocatalytic syntheses of 4-acylcoumarins from 4-chlorocoumarin. The leaving group at the 4-position of the coumarin was replaced by aroyl groups that originate from aromatic aldehydes by NHC-catalyzed umpolung. 4-Acylthiocoumarins and 2-acylquinolin-2-ones were also prepared using this method. These are the first examples of nucleophilic substitutions at the β-carbons of enones to afford γ-ketoenones.     

First nucleophilic aromatic substitution of annelated pyrazole.

3-Chloropyrazolo[3,4-c]quinoline 5, 3-chloropyrazolo[3,4-c]isoquinoline 6, 1,2-dihydro-1,2-dimethylpyrazolo[3,4-c]quinolin-3-one 8, and 1,2-dihydro-1,2-dimethylpyrazolo[3,4-c]isoquinolin-3-one 10 were obtained by acid-induced nucleophilic aromatic substitution (S(N)H) of H-3 in N-hydroxypyrazolo[3,4-c]quinoline 1b and in N-hydroxy pyrazolo[3,4-c]isoquinoline 3b. In the acid-induced chlorination, 3b was far more reactive than 1b, whereas the related N-hydroxypyrazolo[4,3-c]quinoline 2b and N-hydroxypyrazolo[4,3-c]isoquinoline 4b were completely unreactive toward S(N)H under identical conditions.     

几种醇类的固态电致化学发光-高效液相色谱检测

使用水／油反相微乳法合成包埋联吡啶钌（Ru（bpy）3^2＋）的纳米硅球（RuSiNPs）,利用Nation材料固定RuSiNPs于玻碳电极上,构筑了RuSiNPs／Nafion复合膜修饰传感电极,进行了醇类的电致化学发光一高效液相色谱（ECL-HPLC）分离检测．利用循环伏安等方法考察了RuSiNPs／Nafion复合膜电极的电化学和ECL行为,结果表明包埋在硅球里的Ru（bpy）32＋较好地保持了原有的光学和电化学性质．研究了实验条件对其ECL的影响,通过HPLC条件的优化建立了利用RuSiNPs／Nafion固态ECL进行醇类样品的分离检测方法,所提出方法对甲醇、乙醇、丙醇和丁醇的检测下限分别为6．7×10^5,8．2×10^5,3．9×10^-4和4．2×10^-4mmol／L．方法被初步应用于一些啤酒样品中醇的检测．     

Switching pathways: room-temperature neutral solvolysis and substitution of amides

Stick or twist: By introducing steric hindrance at the nitrogen atom, stable linear amides bearing an electron-withdrawing α-substituent (Z = Ar, PhSO(2), P(O)(OR)(2), CN, or CO(2)R) can be induced to undergo solvolysis and substitution reactions through an elimination-addition mechanism (see picture). Key to this process is a low barrier to rotation around the amide bond and the α-substituent?Z.     

Inversion of configuration of alcohols through nucleophilic displacement promoted by nitrate ions.

Inversion of configuration of hydroxy functionalities in biologically significant structures has been performed under mild conditions through nucleophilic displacement by nitrate ion.     

Oxidative nucleophilic substitution: transformation of alkylboronic derivatives

An efficient amidation reaction is described in this paper. Potassium alkyltrifluoroborate salts can be transforming to amides from nitriles in the presence of copper acetate and boron trifluoride. An extension of this reaction allowed the formation of amines, ethers, and C-C bond.     

Selective ortho methylation of nitroheteroaryls by vicarious nucleophilic substitution

An efficient and scalable three-step one-pot approach to 6-methyl-5-nitroisoquinoline (1) from inexpensive 5-nitroisoquinoline, utilizing the vicarious nucleophilic substitution (VNS) as a key step, is described. The optimized reaction conditions can be applied to a limited number of other aromatic and heteroaromatic nitro compounds. Attempts to understand the observed selectivity in the VNS step led to the discovery of two new reaction pathways under VNS conditions, one leading to an isoxazole and the other resulting in the formal cyclopropanation of an aromatic nitro compound.     

Poly(Aryl ethers) by nucleophilic aromatic substitution. II. Thermal stability

The thermal stability and degradation process for a specific poly(aryl ether) system have been studied. In particular, the polymer which is available from Union Carbide Corporation as Bakelite polysulfone has been examined in detail. Polysulfone can be prepared from 2,2-bis(4-hydroxyphenyl)propane and 4,4′-dichlorodiphenyl sulfone by nucleophilic aromatic substitution. Because of a low-temperature transition at ? 100°C. and a glass transition at 195°C., polysulfone retains useful mechanical properties from ?100°C. to 175°C. A number of experimental methods were utilized to study the thermal decomposition process for this polymer system. Polysulfone gradually degraded in vacuum above 400°C. as demonstrated by mass spectrometry. Thermogravimetric analysis in argon, air, or high vacuum indicated that rapid decomposition began above 460°C. From gas chromatography, mass spectrometry and repeated laboratory pyrolyses, a number of products from polymer decompositions were identified. The most important degradation process in vacuum or inert atmosphere was loss of sulfur dioxide. Several model compounds representative of portions of poly(aryl ether) molecules were synthesized and the relative thermal stabilities determined. Possible mechanisms for pure thermal decomposition of polysulfone were derived from the product analyses, model studies, and consideration of bond dissociation energies.     

Synthesis of anacardic acids by nucleophilic substitution on 2-aryloxazolines

A new direct synthesis for anacardic acids based in a nucleophilic substitution of a methoxy group in 2-aryloxazolines by long-chained Grignard reagents is reported.     

Alkanoylation of quinazoline by nucleophilic aromatic substitution: Combined experimental and computational study

A combined experimental and computational study on the key intermediates of NHC-catalyzed acylation reaction, Breslow intermediates (BIs), has been conducted in order to achieve a direct nucleophilic alkanoylation of N-heterocycles. Various BI precursors are alternatively prepared and used in the reaction with 4-chloroquinazoline. The present study reveals that the intermediates having benzimidazole moiety serve as acylating agents for the introduction of straight-chain alkanoyl groups. Natural bond orbital analysis indicates that the reactivity of intermediates partly correlates to the occupancy of the π_C-C bonds of the hydroxyl enamine moieties. The putative rate-determining step of the acylation reaction has been theoretically investigated. Several new 4-alkanoylquinazolines are synthesized using the BI precursors.