MoCl5参与的苯甲醚与叔丁醇的烷基化反应

研究了五氯化钼参与的苯甲醚和叔丁醇在正己烷溶剂中的烷基化反应,结果显示出很高的对位选择性。当苯甲醚∶叔丁醇∶五氯化钼的比为1∶1.2∶1时,4-叔丁基苯甲醚的收率达到94%,2,4-二叔丁基苯甲醚的收率仅有6%,没有2-叔丁基苯甲醚产物生成,邻对位选择性100%,苯甲醚转化率100%。改变反应条件,当苯甲醚∶叔丁醇∶五氯化钼的比为0.5∶1∶1时,反应时间0.5小时,可以得到43%收率的2,4-二叔丁基苯甲醚。研究数据表明五氯化钼比五氯化铌、五氯化钽,有更高的反应活性和选择性。当醚∶醇∶金属卤化物比为1∶1.2∶1时,上述三种Lew is酸对应的4-叔丁基苯甲醚的收率分别为94%(1h)、82%(2h)、40%(1h)。     

Electronic structure,spectra, and thermodynamical functions of molybdenum pentachloride

The SCF-X -SW method in non-relativistic and quasi-relativistic versions has been used to calculate the electronic structure, ionization potentials, energies and oscillator strengths of the optical transitions in MoCl₅. The electronic absorption spectrum of the gaseous MoCl₅ has been measured. The interpretation of the photoelectron and optical spectra of MoCl₅ is given. Spinpolarization effects and relativistic corrections are discussed. The thermodynamical functions of MoCl₅ (gas) are calculated.     

An efficient synthesis of 3‐hydroxychromone using niobium pentachloride

A new and efficient 2‐step synthesis of 3‐hydroxychromone is described. Commercially available chromone is converted to the corresponding epoxide which is rearranged with niobium pentachloride to 3‐hydroxychromone in 61% overall yield.     

Reductive monoalkylation of nitro aryls in one-pot

The scope of the serendipitous reductive monoalkylation of ethyl (4-methoxy-3-nitrophenyl) acetate taking place during reduction of the nitro functionality to the corresponding primary amine when treated with hydrogen (1 atm) over Pd/C (10%) in ethanol is investigated. Upon prolonged reaction time the reaction conducted in ethanol and methanol yields significant amount of the corresponding secondary amines, while when performed in n-butanol and i-propanol it only resulted in the formation of a small amount of the corresponding secondary amines. Further development of the reductive monoalkylation reaction provided conditions that facilitate conversion of a range of different nitro aryls in one-pot to the corresponding secondary benzyl amino aryls in mostly good to excellent yields. This is accomplished by using hydrogen (1 atm) over Pd/C (10%) as reducing agent and benzaldehyde as the benzyl source combined with a stepwise reaction sequence. This chemistry was further extended to the formation of substituted benzyl amino aryls. The yields of the latter products varied dramatically depending on the substitution patterns associated with the benzaldehyde. However, by altering the reaction conditions it was possible to improve the yields of the benzylated products.     

Reactions of biscyclopentadienylnickel with lithium and magnesium aryls

The reaction of nickelocene with phenyllithium, ortho-, meta- and para-methylphenylmagnesium bromide, and 2-((dimethylamino)methyl) phenyllithium are studied. It was found that unstable compounds {CpNiC₆H₄R} (R = H, o-, m-, p-CH₃) are formed in those reactions. For R = CH₂N(CH₃)₂, a stable compound, CpNiC₆H₄CH₂N(CH₃)₂, is formed due to intramolecular coordination. In other cases, mainly coupling reactions occur and biphenyl, bitolyl and higher coupling products are formed. Compound (CpNiC₆H₄R) is also formed as a product of thermal decomposition of Cp{η²⁻ C₂H₄)NiC₆H₄R. It reacts further to form the same products as above. The mechanism of the coupling reactions is proposed and discussed.     

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.     

Oxidative transformation of azides to aryl nitriles using DIB/TBHP: scope and mechanistic insights

Bis(tert-butylperoxy)iodobenzene, generated in situ by the reaction between diacetoxyl iodobenzene (DIB) and tert-butyl hydroperoxide (TBHP), was used in the oxidative transformation of primary azides to nitriles, and secondary azides to ketones.     

Modified procedure for the synthesis of 2-chloroquinoline-3-carbaldehydes using phosphorus pentachloride

An alternative, convenient, and efficient procedure for the synthesis of 2-chloroquinoline-3-carbaldehyde was carried out by the action of Vilsmeier’s reagent on acetanilides using phosphorus pentachloride as chlorinating agent in place of phosphoryl chloride, obtaining good yields for activated acetanilides. The optimal conditions for this reaction requires only 4.5 equivalents of phosphorus pentachloride, 3 equivalents of N,N-dimethylformamide, and 1 equivalent of the corresponding acetanilide at 100 °C for approximately 4 h.     

Oxidative transformation of 1,3-dioxacycloalkanes induced by chlorine dioxide

The products and kinetic regularities of the reactions of 1,3-dioxacycloalkanes with chlorine dioxide were studied. The effects of the nature of solvent and the temperature on the reaction rate were considered and the activation parameters were determined.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1688–1692, August, 2004.Deceased.     

Mechanisms of methane activation and transformation on molybdenum oxide based catalysts

We present a comprehensive survey of different C-H activation pathways over various kinds of active sites of terminal oxygens [=O] and bridge oxygens [-O-] by using Mo3O9 model systems. This allows us to provide some insights into fundamental issues concerning C-H activation by metal oxo species involved in many heterogeneous, homogeneous, and enzymatic processes. We show that H abstraction is the most feasible reaction pathway for the activation of a C-H bond on molybdenum oxides; and that [=O] is more active than [-O-]. Our calculations also suggest that (2+2) can be an alternative if M=O bond possesses a high polarity, while (5+2) can provide another effective pathway if two M=O bonds are in close proximity. Implications for the related heterogeneous, homogeneous, and enzymatic processes are discussed.