Inter- and intramolecular palladium-catalyzed allyl cross-coupling reactions using allylindium generated in situ from allyl acetates, indium, and indium trichloride

Inter- and intramolecular palladium-catalyzed allyl cross-coupling reactions using allylindium generated in situ by treatment of allyl acetates with indium and indium trichloride in the presence of Pd(0) catalyst and nBuNMe(2) in DMF were successfully demonstrated. Allylindium species generated in situ by reductive transmetalation of pi-allylpalladium(II) complexes, obtained from a variety of allyl acetates in the presence of Pd(0) catalyst together with indium and indium trichloride, were found to be capable of acting as effective nucleophilic coupling partners in Pd-catalyzed cross-coupling reactions. A variety of allyl acetates such as but-1-en-3-yl acetate, crotyl acetate, and 2-methylallyl acetate afforded the corresponding allylic compounds in good yields in cross-coupling reactions. Various electrophilic cross-coupling partners such as aryl iodides and vinyl bromides and triflates participate in these reactions. Not only intermolecular but also intramolecular Pd-catalyzed cross-coupling reactions work equally well to produce the desired allylic coupling products in good yields.     

Vibrational spectra and thermodynamic functions of allyl acetate

Raman spectrum of allyl acetate molecule has been photographed in liquid phase using 4358 ? line of mercury arc as the exciting line. Infrared absorption spectrum of the molecule has been recorded in liquid phase in the frequency range 200–4000 cm⁻¹. Both the spectra have been analysed to identify the fundamental frequencies. AssumingC _s symmetry, the observed fundamental frequencies have been assigned to various modes of vibration and compared with the frequencies of allyl halides and acetic acid. On the basis of present assignments of fundamental vibrational frequencies and assumed approximate structural parameters of the molecule, thermodynamic functions have been computed.     

乙酸烯丙酯的氢硅化反应

本文在对芳醛及环酮的氢硅化反应研究基础上, 进一步研究乙酸烯丙酯的氢硅化反应。(Ph~3P)~3RhCl作催化剂, 反应可在均相进行。采用假一级动力学方法, 以气相色谱法鉴测氢硅化产物生成的速率, 求得其反应速度常数, 进而分析其反应活性与反应物结构的关系, 并提出相应的可能机理。     

Thermal behaviour of poly(allyl azide)

The paper describes the synthesis of low molecular mass poly(allyl chloride) (PAC) (M _n= 856-3834 g mol^-1) using Lewis acid (ALCL₃, FeCL₃, TiCL₄) and al powder. Branching in PAC was indicated on the basis of elemental analysis and ¹H-NMR spectroscopy. azidation of pac could be carried out at 100°C by using NaN₃ and DMSO as solvent. Curing of poly(allyl azide) (PAA) by cyclic dipolar addition reaction with EGDMA (ethylene glycol dimethacrylate, 5-45 phr) was investigated by differential scanning calorimetry and structure of cured polymer was confirmed by FTIR. A two-step mass loss was exhibited by uncured and cured PAA in nitrogen atmosphere. A mass loss of 20-28% (155-274°C) and 50-61% (330-550°C) was observed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Formation of organopalladium complexes on SiO2 and Al2O3 as a result of the reaction of allyl alcohol with supported PdCl2; thermal decomposition of these complexes

It was established by electronic spectroscopy in the UV and visible regions and mass spectrometry that when allyl alcohol reacts from the gas phase with palladium chloride supported on SiO₂ and Al₂O₃ a complex similar in characteristics to a bis--allylpalladium chloride complex that is fixed on the surface of the support is formed. Decomposition of this complex in vacuo occurs at 135°C with the formation of allyl chloride and zero-valence supported palladium.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1536–1539, July, 1992.     

ZrCl4 as a mild and efficient catalyst for the one-pot conversion of TBS and THP ethers to acetates

A mild, efficient and chemoselective method has been developed for the direct transformation of tert-butyldimethylsilyl and tetrahydropyranyl protected alcohols into the corresponding acetates with acetic anhydride and zirconium(IV) chloride as the catalyst in acetonitrile, in a one-pot reaction with high yields and short reaction times. This method has been applied to a variety of substrates.     

二甲基烯丙基对甲基苄基氯化铵的合成与表征

以对甲基氯化苄与二甲基烯丙基胺为原料合成了二甲基烯丙基对甲基苄基氯化铵,考查了光照、氮气保护、避光、温度、原料配比、反应时间和不同溶剂等因素对反应的影响,通过四苯硼钠的定量分析确立了最佳反应条件,并对产物的结构进行了表征.     

水吸收气相色谱法测定环境空气中丙烯醇

建立气相色谱法测定环境空气中丙烯醇的方法。用蒸馏水吸收环境空气中的丙烯醇,以DB–624色谱柱(30 m×0.53 mm,3μm)为分离色谱柱,用氢火焰离子化检测器检测丙烯醇的含量。当采样体积为30 L时,丙烯醇的检出限为0.01 mg/m~3,样品加标回收率为93.0%~97.4%,测定结果的相对标准偏差小于2%(n=7)。该方法前处理简便,分析灵敏度高,分析过程中避免了有机溶剂的使用,无二次污染,适用于环境空气中丙烯醇的监测。     

Theoretical reinvestigation of the ozonolysis mechanism of allyl alcohol

Allyl alcohol (AA) is the simplest unsaturated alcohol. Ozonolysis is one of the key removal processes for AA in the atmosphere. However, a recent theoretical study suggests that the ozonolysis of AA cannot feasibly occur in atmospheric conditions because of the high barrier (~96 kcal/mol) involved in the primary ozonide (POZ) decomposition. In this work, the ozonolysis mechanism of AA was reinvestigated theoretically. The computed barrier for POZ decomposition is only ~20 kcal/mol. Therefore, the AA ozonolysis can take place in the atmosphere, consistent with the experimental conclusions. Moreover, two new Criegee intermediates (syn- and anti-AA-CI) were found to be produced in this reaction. The wave function analyses indicate that there exists an intermolecular hydrogen bond in syn-AA-CI, which significantly affects its unimolecular decomposition and reactions with H₂O. Compared with the normal reactions of anti-CI-AA, the stabilized syn-AA-CI has two distinct isomerization channels: (i) addition of OH group to the reactive sites of CI forming an ethylene oxide (HOOCH₂OCH₂) and (ii) double H-transfer producing HOOCH₂CHO. Meanwhile, the addition of H₂O in syn-AA-CI also exhibits two different pathways. One is the unique addition-coupled double H-transfer, and the other is the addition-coupled single H-transfer, both leading to the formation of CH₂(OH)CH(OH)OOH.     

Catalysis of a free radical allylic displacement by allyl iodide

The preparation of allyl chlorostannan 5 was achieved into two steps via free radical displacement of the sulphone group by tributyltin radical. The chemical structure of compound 5 was confirmed by normal spectroscopic methods, including NMR, IR and MS. The mechanism for the free radical reaction of chlorosulphone 6 with tributyltinhydride is likely to proceed via the catalysis of the trace amount of the iodoallyl chloride 4.     

A mild, highly selective and remarkably easy procedure for deprotection of aromatic acetates using ammonium acetate as a neutral catalyst in aqueous medium

Ammonium acetate was found to catalyze efficiently the selective deprotection of aromatic acetates in the presence of various sensitive functionalities in aqueous methanol under neutral conditions at room temperature to yield the corresponding phenols in excellent yields. The method has been utilized for deprotection of acetates of several naturally occurring bioactive phenolic compounds and for preparation of venkatasin, a natural coumarino-lignan, from the anticancer compound cleomiscosin A.     

An efficient palladium-catalyzed Heck coupling of aryl chlorides with alkenes

Catalyst system PdCl₂(PCy₃)₂/Cs₂CO₃ in dioxane was found to be the efficient catalyst system for Heck cross-coupling reactions of deactivated, neutral, and activated aryl chlorides with a variety of alkenes under mild conditions to afford selectively E-arylated alkenes in good to excellent yields.     

Triethylborane as an efficient promoter for palladium-catalyzed allylation of active methylene compounds with allyl alcohols

Without prior activation of allyl alcohols, allylation of a variety of active methylene compounds with allyl alcohols proceeds smoothly at rt-50°C in the presence of catalytic amounts of Pd(OAc)₂ (1-10 mol%), Et₃B (30-240 mol%), a phosphine ligand (1-20 mol%), and a base (0 to 50-60 mol%).     

Cascade synthesis of dihydrobenzofuran via Claisen rearrangement of allyl aryl ethers using FeCl3/MCM-41 catalyst

Dihydrobenzofuran as one of the active ingredients of the naturally occurring motif is synthesized by using in situ generation of ortho allyl phenols. Aryl allyl ethers on reacting with catalytic amounts of non noble metal iron (III) chloride supported on MCM-41 under moderate reaction conditions yield dihydrobenzofuran. First step via Claisen rearrangement gives ortho allyl phenol followed by its in situ cyclization to yield dihydrobenzofuran in very good yields. Both Lewis as well as Brønsted acidity of the catalyst as evidenced by Py-FTIR studies was found to catalyze the cascade synthesis of dihydrobenzofuran. The scope of the present strategy was successfully demonstrated for several substrates with varying electronic effects for the synthesis of corresponding dihydrobenzofuran with high yields in a range of 71–86%.     

An effective one-pot conversion of acid chlorides to aldehydes and ketones

Aldehydes and ketones were synthesized from their respective acid chlorides via a one-pot protocol. Morpholine amide intermediates that were readily prepared by the aminolysis of various acid chlorides with diisobutyl(morpholino)aluminum smoothly reacted with the reducing agent LDBMA and the organolithium reagents under mild reaction conditions (0 °C), giving almost excellent product yields of up to 95%.     

Epoxidation of allyl chloride with H_2O_2 on Ti-ZSM-5 prepared by the isomorphous substitution

The epoxidation of allyl chloride with H2O2 on Ti-ZSM-5 prepared by isomorphous substitution of HZSM-5 with TiCl4 gas was studied. The results show that Ti-ZSM-5 has a high catalytic efficiency for the epoxidation of allyl chloride. The H2O2 utilization reaches 99.50% when the allyl chloride/H2O2 molar ratio is > 1. The effect of solvent species, catalyst concentration, H2O2 and allyl chloride concentration and reaction temperature on the epoxidation was investigated simultaneously. It is found that methanol is the best solvent for the reaction. The reaction rate equation with v = k[Cat. ] [H2O2]1/2-[C3H5Cl] and the apparent activation energy with Ea = 63.462 kJ/mol are obtained according to the kinetics study.     

Direct and remarkably efficient conversion of methane into acetic acid catalyzed by amavadine and related vanadium complexes. A synthetic and a theoretical DFT mechanistic study

Vanadium(IV or V) complexes with N,O- or O,O-ligands, i.e., [VO{N(CH2CH2O)3}], Ca[V(HIDPA)2] (synthetic amavadine), Ca[V(HIDA)2], or [Bu4N]2[V(HIDA)2] [HIDPA, HIDA = basic form of 2,2'-(hydroxyimino)dipropionic or -diacetic acid, respectively], [VO(CF3SO3)2], Ba[VO(nta)(H2O)]2 (nta = nitrilotriacetate), [VO(ada)(H2O)] (ada = N-2-acetamidoiminodiacetate), [VO(Hheida)(H2O)] (Hheida = 2-hydroxyethyliminodiacetate), [VO(bicine)] [bicine = basic form of N,N-bis(2-hydroxyethyl)glycine], and [VO(dipic)(OCH2CH3)] (dipic = pyridine-2,6-dicarboxylate), are catalyst precursors for the efficient single-pot conversion of methane into acetic acid, in trifluoroacetic acid (TFA) under moderate conditions, using peroxodisulfate as oxidant. Effects on the yields and TONs of various factors are reported. TFA acts as a carbonylating agent and CO is an inhibitor for some systems, although for others there is an optimum CO pressure. The most effective catalysts (as amavadine) bear triethanolaminate or (hydroxyimino)dicarboxylates and lead, in a single batch, to CH3COOH yields > 50% (based on CH4) or remarkably high TONs up to 5.6 x 103. The catalyst can remain active upon multiple recycling of its solution. Carboxylation proceeds via free radical mechanisms (CH3* can be trapped by CBrCl3), and theoretical calculations disclose a particularly favorable process involving the sequential formation of CH3*, CH3CO*, and CH3COO* which, upon H-abstraction (from TFA or CH4), yields acetic acid. The CH3COO* radical is formed by oxygenation of CH3CO* by a peroxo-V complex via a V{eta1-OOC(O)CH3} intermediate. Less favorable processes involve the oxidation of CH3CO* by the protonated (hydroperoxo) form of that peroxo-V complex or by peroxodisulfate. The calculations also indicate that (i) peroxodisulfate behaves as a source of sulfate radicals which are methane H-abstractors, as a peroxidative and oxidizing agent for vanadium, and as an oxidizing and coupling agent for CH3CO* and that (ii) TFA is involved in the formation of CH3COOH (by carbonylating CH3*, acting as an H-source to CH3COO*, and enhancing on protonation the oxidizing power of a peroxo-VV complex) and of CF3COOCH3 (minor product in the absence of CO).     

An efficient conversion of berberine into a rhoeadine via an indenobenzazepine

Treatment of ketoaziridine $\text{4}$ with aqueous formaldehyde gives the unusual bridged indenobenzazepine derivative $\text{6}$ whose reduction uith sodium cyanoborohydride produces trans ketol $\text{8}$. In the presence of hydrochloric acid, $\text{8}$ undergoes irreversible conversion to the more stable cis ketol $\text{10}$. Periodate oxidation of $\text{8}$ supplies γ-laotone $\text{11}$. NaBH₄ reduction of $\text{11}$ followed by acid treatment affords δ-lactone $\text{12}$ which upon reduction and O-methylation furnishes cis rhoeadine analog $\text{14}$.