氨基脲催化下碳亲核试剂和氮亲核试剂对查尔酮的Michael加成反应

以查尔酮、丙二酸酯、丙二腈、苯胺为原料,水为溶剂,苯丙氨酸脲化合物为催化剂,三氟甲磺酸为助剂60℃下反应,高产率得到Michael加成产物.该方法具有催化剂合成简单、环境友好等优点.     

Radiation-Induced Addition Reaction of Ethyl Mercaptan and Carbon Tetrachloride to 1,2-Polybutadiene

γ-Ray-induced addition reactions of syndiotactic 1,2-polybuta-diene film with various compounds were carried out at room temperature. The weight of the film markedly increased when ethyl mercaptan was used. In the reaction with ethyl mercaptan, only addition took place without crosslinking. The addition of ethyl mercaptan to the vinyl group of syndiotactic 1,2-poly-butadiene followed anti-Markownikoff rule, and gave a 1:1 addition product. The rate of addition increased as the crys-tallinity of syndiotactic 1,2-polybutadiene used became lower. A similar relation between the crystallinity and the rate of addition was also observed in the γ-ray-induced addition of carbon tetrachloride to syndiotactic 1,2-polybutadiene, but at the same time gelation was pronounced. When liquid 1,2-polybutadiene was used instead of syndiotactic-1,2-polybutadiene, gelation which made the polymer insoluble in carbon tetrachloride did not take place, although a crosslinking reaction was noted. The appearance of the product in this case changed from a viscous liquid to a white powder as the reaction proceeded. The addition of carbon tetrachloride to the vinyl group of liquid 1,2-polybutadiene was also of the anti-Markownikoff type. This addition was accompanied by unexpectedly large vinyl consumption. The total decrease in vinyl group was found to be much larger than the decrease in vinyl group which was brought about by the addition of carbon tetrachloride. This discrepancy was attributed to cyclization and crosslinking reactions which were ascribed to the vinyl group bound by the main chain.     

Gas-Liquid Chromatography-Mass Spectrometry of Some Arene Tricarbonylchromium Complexes

Abstract

The gas-liquid chromatography-mass spectrometry of a number of arene tricarbonylchromium complexes has been investigated. The combined technique readily demonstrates that substituted benzene π-complexes survive the analysis intact, but a closely related compound, the tricarbonylchromium complex of 2,3-dimethylnaphthalene, has proven to be thermally unstable both on the column and in the molecular separator.     

Tetramethylheptalenes and Their Tricarbonylchromium Complexes: Synthesis,Structures, and Thermal Rearrangements

The thermal 4 : 1 equilibrium mixture of 1,3,5,6- and 1,3,5,10-tetramethylheptalene ( 13a and 13b , resp.) has been prepared, starting from the thermal equilibrium mixture of dimethyl 6,8,10-trimethylheptalene-1,2- and -4,5-dicarboxylate ( 6a and 6b , resp.; cf. Scheme 5). These heptalenes undergo double-bond shifts (DBS) even at ambient temperature. Treatment of the mixture 13a / 13b 4 : 1 with [Cr(CO)₃(NH₃)₃] in boiling 1,2-dimethoxyethane resulted in the formation of all four possible mononuclear Cr(CO)₃ complexes 19a – 19d of 13a and 13b , as well as two binuclear Cr(CO)₃ complexes 20a and 20b , respectively, in a total yield of 87% (cf. Scheme 7). The mixture of complexes was separated by column chromatography, followed by preparative HPLC (cf. Fig. 2). The structures of all complexes were established by X-ray crystal-structure analyses (complex 19b and 20b ; cf. Figs. 6 – 8) and extensive ¹H-NMR measurements (cf. Table 3). In 20b , the two Cr(CO)₃ groups are linked in a `syn'-mode to the highly twisted heptalene π-skeleton. The correspondence of the <sup>1</sup>H-NMR data of 20a with that of 20b indicates that the two Cr(CO)<sub>3</sub> groups in 20a also have a `syn'-arrangement. The thermal behavior of the mononuclear complexes 19a – 19d has been studied at 85° in hexafluorobenzene (HFB). At this temperature, all four complexes undergo rearrangement to the same thermal equilibrium mixture (cf. Table 8). The rates for the thermal equilibration of each complex have been determined by ¹H-NMR measurements (cf. Figs. 9 – 12) and analyzed by seven different kinetic schemes (Chapt. 2). The equilibration rates are in agreement with two different haptotropic rearrangements that take place, namely intra- and inter-ring shifts of the Cr(CO)₃ group, whereby both rearrangements are accompanied by DBS of the heptalene π-skeleton (cf. Scheme 9). All individual kinetic steps possess similar ΔG^≠ values in the range of 29 – 31 kcal⋅mol⁻¹ (cf. Table 8). The occurrence of inter-ring haptotropic migrations of Cr(CO)₃ groups has already been established for anellated aromatic systems (cf. Scheme 10); however, it is the first time that these rearrangements have been unequivocally demonstrated for Cr(CO)₃ complexes of non-planar bicyclic [4n]annulenes, such as heptalenes. The mechanism of migration may be similar to that proposed for aromatic systems (cf. Schemes 10 and 11).     

Asymmetric Synthesis of Chiral Sulfimides through the O-Alkylation of Enantioenriched Sulfinamides and Addition of Carbon Nucleophiles

Chiral sulfimides, the aza-analogues of sulfoxides, are valuable compounds in organic synthesis and medicinal chemistry. Herein, we report an efficient method for preparing chiral sulfimides from easily available enantioenriched sulfinamides. The key step of this method is a stereospecific oxygen-selective alkylation of enantioenriched sulfinamides, which is accomplished by using isopropyl iodide, K₂CO₃, and DMPU. The resulting chiral sulfinimidate esters are transformed to chiral sulfimides by the nucleophilic addition of the Grignard reagents under simple conditions. This transformation enables access to the enantioenriched diaryl or dialkyl sulfimides bearing two similar carbon substituents, which are difficult to synthesize by previous methods.     

Carbon versus Sulfur Addition of Nucleophiles to Sulfines. Part I. The Case of Sulfinates

The nucleophilic substitution of chlorine in chlorosulfines with arylsulfinates leads to sulfonylsulfines with complete inversion of configuration within the starting sulfines. A mechanism for this displacement reaction is proposed. The sulfonylsulfines show good reactivity as heterodienophiles and the reaction with acyclic 1,3-dienes is surprisingly regio- and diastereoselective. The stereochemical details were established by X-ray crystallography and the competitive dienophilic properties were examined.     

Gallium Trihalide Catalyzed Sequential Addition of Two Different Carbon Nucleophiles to Esters by Using Silyl Cyanide and Ketene Silyl Acetals

A sequential addition of silyl cyanide and ketene silyl acetals to esters was achieved by a gallium trihalide catalyst to produce β‐cyano‐β‐siloxy esters. This is the first example of the sequential addition of two different carbon nucleophiles to esters. The employment of lactones provided α,α‐disubstituted cyclic ethers with a cyano group and an ester moiety. A variety of esters and lactones are applicable to this reaction system.     

Copper-Catalyzed Enantio- and Diastereoselective Addition of Silicon Nucleophiles to 3,3-Disubstituted Cyclopropenes

A highly stereocontrolled syn-addition of silicon nucleophiles across cyclopropenes with two different geminal substituents at C3 is reported. Diastereomeric ratios are excellent throughout (d.r.≥98:2) and enantiomeric excesses usually higher than 90 %, even reaching 99 %. This copper-catalyzed C−Si bond formation closes the gap of the direct synthesis of α-chiral cyclopropylsilanes.     

Addition of Nucleophiles to Fragment Ions in Mass Spectrometers under Electrospray-Ionization Conditions

Mass spectra of several aromatic compounds containing an amino or thiol group were recorded under electrospray conditions with a Finnigan TSQ 700, as well as on a Bruker Esquire-LC spectrometer. The MS/MS spectra displayed two main peaks: the first one arising from the cleavage of the amino or thiol group; the second one appeared at 18 Da higher than the first one. It could be shown that the second peak resulted from a nucleophilic addition of one water molecule to the fragment ion.     

Catalytic Activity of Immobilized Transition Metal Complexes with Monoethanolamine in Carbon Tetrachloride Addition to Multiple Bonds

The rates of CCl₄ addition to octene-1 in the presence of monoethanolamine complexes with Mn, Cu, V, Co, and Ni ions immobilized on the surface of silica have been determined. The majority of catalysts exhibit an inverse dependence of relative catalytic activity on surface metal concentration. Changes in the total concentrations and ligand environments of paramagnetic ions in the course of reaction are studied by EPR spectroscopy for copper- and vanadyl-containing catalysts. It has been found that the activity of complexes correlates with the rate of reduction of a metal ion in the course of a catalytic reaction.     

Convenient synthesis of fluorinated quinoline, 1,2-dihydroquinoline, and 1,2,3,4-tetrahydroquinoline derivatives

A convenient synthetic method for 2-polyfluoroalkylated quinoline systems through the efficient generation of perfluoroalkylated imine from o-vinylanilines with perfluorinated hemiacetals or aldehyde hydrates was developed. In most cases, the major products are 2-polyfluoroalkyl-1,2-dihydroquinoline derivatives 3, which can be converted to either quinolines or 1,2,3,4-tetrahydroquinolines.     

Distinctive Characteristics of Carbon Tetrachloride Addition to Olefins in the Presence of Copper Complexes with Donor Ligands

The interaction between CCl₄and olefins with different structures is studied in the presence of copper complexes with P-, S-, and N-containing donor ligands. Kinetic and spectroscopic studies show that the ability of olefins to be coordinated to copper complexes governs the rate, the product composition, and the reaction mechanism. Depending on the olefin and the structure of the metal complex, either typical radical-chain reactions or processes without free radicals are observed.