Synthesis of benzodiazocine-annulated heterocycles by the implementation of Pd-catalyzed intramolecular Heck reaction

Synthesis of hitherto unreported benzodiazocine-annulated heterocycles by the implementation of palladium-catalyzed intramolecular Heck reaction has been achieved in excellent yields.     

Rapid access to homoallylic alcohols via Pd(OAc)2 catalyzed Barbier type allylation in presence of DMAP

DMAP was found to accelerate significantly the rate of Pd(OAc)₂ catalyzed Barbier type allylation of carbonyl compounds by allylbromide using SnCl₂·2H₂O as reducing agent. Both aldehyde as well as ketones produced excellent yields within a short reaction time in the presence of 3 mol % of Pd(OAc)₂ and 12 mol % of DMAP at room temperature. Aldehydes could be allylated within 5–10 min whereas, in case of ketones, the reaction completes in 45–120 min.     

Regioselective ortho-hydroxylation of aryl moiety of 2-arylpyridines using Pd(OAc)2/Oxone in PEG-3400/tert-BuOH

Regioselective ortho-hydroxylation of aryl moiety of 2-arylpyridines was carried out under the influence of Pd(OAc)₂/Oxone (potassium peroxymonosulfate) in PEG-3400/t-BuOH in moderate yields.     

An expedient synthesis of indolo[1,2-a]quinolines via Mn(OAc)3-mediated oxidative free radical cyclization and NaI/O2-assisted dealkoxycarbonylation/aerobic oxidation cascade

An expedient synthetic procedure of indolo[1,2-a]quinolines was developed using a sequential Cu-mediated N-arylation of indole, Mn(OAc)₃-mediated oxidative free radical cyclization, and NaI/O₂-assisted concomitant dealkoxycarbonylation/aerobic oxidation. The last step was replaced by a palladium-catalyzed decarboxylation/elimination protocol for the allyl ester derivatives.     

Pd(OAc)2-catalyzed C-H activation of indoles: a facile synthesis of 3-cyanoindoles

Indoles undergo smooth cyanation with CuCN in the presence of 20 mol % Pd(OAc)₂ and 40 mol % CuBr₂ in DMF to produce a wide range of the corresponding 3-cyanoindoles in good yields with high regioselectivity.     

Synthesis and structure of C2-symmetric N-heterocyclic carbene complexes of palladium

The first 9- and 11-membered cis and trans C₂-symmetric benzimidazol-2-ylidene palladium(II) complexes based on a trans-2,2-dimethyl-1,3-dioxalane backbone were synthesised and the configuration of the complexes was elucidated via NMR and X-ray crystallography.     

Synthesis and reactivity of N-hydroxy-2-aminoindoles

Catalytic hydrogenation of (2-nitrophenyl)acetonitriles bearing an electron-withdrawing substituent α to the nitrile, using Pd/C and (Ph₃P)₄Pd, affords N-hydroxy-2-aminoindoles in good to excellent yields. (Ph₃P)₄Pd decreases the reduction rate of the intermediate hydroxylamine and acts as a catalyst during the cyclization onto the nitrile.     

Synthesis of branched carbasugars via photooxygenation and manganese(III) acetate free radical cyclization

Transformation of cyclohexa-1,3- and 1,4-dienes to carbasugars is described. Photooxygenation of dienes gave bicyclic endoperoxides, which were reduced with thiourea to the corresponding 1,4-diols with cis-configuration. Lactonization of the remaining double bond by oxidative addition of acetic acid to the double bond in the presence of Mn(OAc)₃ followed by lactone ring-opening reaction gave the target branched carbasugars.     

Synthesis and characterization of piperazine-substituted dihydrofuran derivatives viaMn(OAc) 3 mediated radical cyclizations

The aim of this study is to synthesize novel piperazine-containing dihydrofuran compounds (3a-n)from radical additions and cyclizations of diacyl and alkyl-acyl piperazine derivatives (1a-h) with 1,3-dicarbonyl compounds (2a-c) mediated by Mn(OAc) ₃ for the first time. From the reactions of 1a-c with dimedone (2a);1a, 1c, and 1d with acetylacetone (2b); and 1a with ethylacetoacetate(2c) ,the dihydrofuran-piperazine compounds 3a-c, 3d-f, and 3g were obtained in medium to high yields (31%–81%), respectively. In addition, dihydrofuran-piperazine compounds 3h-j and 3k-n were prepared at low to medium yields (20%–40%) from the reactions of 1e-g with 2a and 1e-h with 2c , respectively.     

A convenient method for the Ru(0)-catalyzed regioselective deuteration of N-alkyl-substituted anilines

A highly effective and operationally practical method for the regioselective deuteration of N-alkyl-substituted anilines employing Ru₃(CO)₁₂ (?1 mol %) as catalyst and D₂O as deuterium source was described. A variety of N-alkyl-substituted anilines were efficiently deuterated (up to 98%) at the ortho and/or para position with respect to the nitrogen at neutral conditions. Under the present conditions, deuterated anilines can be easily obtained with simple extraction and evaporation. Substituents with aromatic methoxy groups would not influence the selectivity compared to previous method.     

A facile protocol for the synthesis of mono-N-methyl anilines via formimidate intermediates

A general procedure for the preparation of mono-N-methyl anilines has been developed with excellent yields. This protocol relies on a NaBH₃(OAc) reduction of formimidate intermediates that are quantitatively generated by treatment of primary substituted anilines with triethyl orthoformate under the catalysis of MCM-41-SO₃H mesoporous zeolite. The newly developed procedure was facile, efficient, and environmentally benign.     

Pd(OAc)2 catalyzed synthesis of 2-aryl- and 2-heteroaryl-benzoxazoles and benzothiazoles in imidazolium ionic liquids (ILs) without additives and with recycling/reuse of the IL

A facile, high yielding, method for the synthesis of a library of 2-aryl- and 2-heteroaryl-benzoxazoles and benzothiazoles from readily available Schiff bases is reported employing catalytic amounts of Pd(OAc)₂ in imidazolium ionic liquids (bmim)BF₄ and (bmim)PF₆ without ligands and/or additives. Simple product isolation and recycling/re-use of the IL are additional advantages of this method.     

PhI(OAc)2/I2-mediated [3+2] reaction of [60]fullerene with amides for the preparation of fullerooxazoles

An efficient synthesis of fullerooxazoles was developed via PhI(OAc)₂/I₂-mediated [3+2] reaction of C₆₀ with amides under photo-irradiation. The reaction was tolerant to various aryl and alkyl amides. The reaction mechanism was investigated in detail and a radical pathway was proposed for the formation of fullerooxazoles. Further transformation of compound 2l allowed the easy conjunction of fullerooxazole moiety to other molecular skeletons.     

An alternative quinoline synthesis by via Friedländer reaction catalyzed by Yb(OTf)3

Quinolines have been synthesized in very good yields from 2-aminoarylketones and differently substituted carbonyl compounds in the presence of Yb(OTf)₃ as the catalyst. The method is applicable to both cyclic and acyclic carbonyl compounds with only slight differences in the experimental procedure.     

Kinetics of homogeneous acetoxylation of cyclododecene and 1,5,9-cyclododecatriene catalyzed by Pd(OAc)2

The kinetics of acetoxylation of cyclododecene and (E,E,E)-1,5,9-cyclododecatriene catalyzed by Pd(OAc)₂ has been studied in glacial acetic acid solutions at 323–343 K and atmospheric pressure. The experimental data were described by kinetic equations of the Michaelis-Menten type.     

Pd(OAc)2/Cu(OTf)2在离子液体BMImPF6中催化苯乙烯二聚反应的研究

在离子液体BMImPF₆中, 用不同的钯催化剂和Lewis酸三氟甲磺酸铜Cu(OTf)₂共催化苯乙烯二聚反应, 发现用Pd(OAc)₂/Cu(OTf)₂作催化剂, Pd/Cu物质的量之比为1～4时, 可高产率高选择性地获得苯乙烯二聚产物1,3-二苯基-1-丁烯. BMImPF₆对催化剂有较好的溶解性, 可固定催化剂体系, 使催化剂有效地与产品分离. 同时, α-甲基苯乙烯的二聚反应表明, 室温下不发生反应, 提高温度有利于反应进行.     

A practical synthesis of 2-(N-substituted)-aminobenzimidazoles utilizing CuCl-promoted intramolecular cyclization of N-(2-aminoaryl)thioureas

A practical protocol for synthesis of 2-(N-substituted)-aminobenzimidazoles was developed. N-(2-Aminoaryl)thioureas undergo a CuCl-promoted intramolecular cyclization to give the corresponding 2-(N-substituted amino)benzimidazoles in good to excellent isolated yields.     

Pd(OAc)2/DABCO-catalyzed Suzuki-Miyaura cross-coupling reaction in DMF

The scope and limitations of the Pd(OAc)₂/DABCO (1,4-diaza-bicyclo[2.2.2]octane)-catalyzed Suzuki-Miyaura cross-coupling reactions have been demonstrated. The results showed that the effect of solvent had a fundamental influence on the reaction. In the presence of Pd(OAc)₂ and DABCO, both aryl bromides and aryl chlorides all worked well with arylboronic acids to form biaryls, heteroaryl-aryls, and biheteroaryls in moderate to excellent yields using DMF as the solvent. Additionally, the reactions of aryl bromides were conducted under relatively mild conditions.     

Stereoselective synthesis of anti-2-oxazolidinones by Ph3P-CCl4-Et3N mediated SN2 cyclization of N-Boc-β-amino alcohols

Ethyl anti-4-substituted phenyl-2-oxo-1,3-oxazolidine-5-carboxylates were synthesized stereoselectively in excellent yields using the Ph₃P-CCl₄-Et₃N system by S_N2 cyclization of N-Boc-β-amino alcohols. syn to anti conversion of ethyl 4-substituted phenyl-2-oxo-1,3-oxazolidine-5-carboxylates using DBU as base is also described.