Copper‐Catalyzed Synthesis of Alkynyl Hydrazones from Alkynes and Hydrazonyl Chlorides

A novel ligand‐free synthesis of alkynyl hydrazones via coupling reaction of hydrazonyl chlorides and terminal alkynes, catalyzed by CuI led to excellent yields.     

Metal Derivatives of Heterocyclic Thioamides: Synthesis and Crystal Structures of Copper Complexes with 1‐Methyl‐1,3‐imidazoline‐2‐thione and 1,3‐Imidazoline‐2‐thione

Reactions of copper(I) halides (Cl, Br, I) with 1‐methyl‐1, 3‐imidazoline‐2‐thione (mimzSH) in 1 : 2 molar ratio yielded sulfur‐bridged dinuclear [Cu₂X₂(μ‐S‐mimzSH)₂(η¹‐S‐mimzSH)₂] (X = I, 1 , Br, 2 ; Cl, 3 ) complexes. Copper(I) iodide with 1,3‐imidazoline‐2‐thione (imzSH₂) and Ph₃P in 1 : 1 : 1 molar ratio has also formed a sulfur‐bridged dinuclear [Cu₂I₂(μ‐S‐imzSH₂)₂(PPh₃)₂] ( 4 ) complex. The central Cu(μ‐S)₂Cu cores form parallelograms with unequal Cu–S bond distances {2.324(2), 2.454(3) Å} ( 1 ); {2.3118(6), 2.5098(6) Å} ( 2 ); {2.3075(4), 2.5218(4) Å} ( 3 ); {2.3711(8), 2.4473(8) Å} ( 4 ). The Cu···Cu separations, 2.759–2.877Å in complexes 1 – 3 are much shorter than 3.3446Å in complex 4 . The weak intermolecular interactions {H₂CH···S^# ( 2 ); CH···Cl^# ( 3 ); NH···I^# ( 4 )} between dimeric units in complexes 2 – 4 lead to the formation of linear 1D polymers.     

Supported Preyssler Nanoparticles in Synthesis of 1,3‐Diaryl‐5‐Spirohexahydropyrimidines

Silica‐supported Preyssler nanoparticles (H₁₄[NaP₅W₃₀O₁₁₀])/SiO₂ are used as a new and recyclable catalyst for the preparation of 1,3‐diaryl‐5‐spirohexahydropyrimidines via a one‐pot condensation of anilines, formaldehyde, and cyclohexanone.     

Copper‐Free Sonogashira Coupling of Acid Chlorides with Terminal Alkynes in the Presence of a Reusable Palladium Catalyst: An Improved Synthesis of 3‐Iodochromenones (=3‐Iodo‐4H‐1‐benzopyran‐4‐ones)

Pd/C is used as an efficient catalyst for the copper‐free Sonogashira coupling of acid chlorides and terminal alkynes to afford ynones in high yields (Tables 1 and 3). Cyclization of (2‐methoxyaryl)‐substituted ynones induced by I₂/ammonium cerium(IV) nitrate (CAN) at room temperature gave 3‐iodochromenones (=3‐iodo‐4H‐1‐benzopyran‐4‐ones) in excellent yield (Table 4).     

Synthesis and Cytotoxicity of 1,4‐Dihydropyridines and an Unexpected 1,3‐Oxazin‐6‐one

Eight heterocycles have been prepared in a one‐pot reaction manner based on the Hantzsch dihydropyridine synthesis. The synthesis afforded seven dihydropyridines (DHP) and one unexpected 1,3‐oxazin‐6‐one. Their structures were confirmed based on NMR spectroscopy and mass spectrometry. The obtained products have been evaluated for their cytotoxicity against eight cancer cell lines and one normal cell line. Two halogenated DHPs ( 7 and 8 ) displayed cytotoxicity toward all the nine tested cancer cell lines with IC₅₀ values from 4.10 to 58.90 μm, while others showed selective activities. DHPs ( 7 and 8 ) bearing a Me group at C(2) and C(6) as well as a halogenated substituent at C(4′) were more antiproliferative than the others.     

Octanuclear Cu(I)‐dithiophosphates: An Efficient Catalyst System for N‐Arylation of Azoles,Amines, and Amides

The formation of a C‐N bond via the cross‐couplings of aryl iodides with azoles, aryl amine, and amides can be successfully achieved in decent yield by the utilization of both [Cu ₈(H){S₂P(OⁱPr)₂}₆]⁺ and [Cu₈{S₂P(OEt)₂}₆]²⁺ as the pre‐catalysts.     

Effective Methods for the Synthesis of N‐Methyl β‐Amino Acids from All Twenty Common α‐Amino Acids Using 1,3‐Oxazolidin‐5‐ones and 1,3‐Oxazinan‐6‐ones

N‐Methyl β‐amino acids are generally required for application in the synthesis of potentially bioactive modified peptides and other oligomers. Previous work highlighted the reductive cleavage of 1,3‐oxazolidin‐5‐ones to synthesise N‐methyl α‐amino acids. Starting from α‐amino acids, two approaches were used to prepare the corresponding N‐methyl β‐amino acids. First, α‐amino acids were converted to N‐methyl α‐amino acids by the so‐called ‘1,3‐oxazolidin‐5‐one strategy’, and these were then homologated by the Arndt–Eistert procedure to afford N‐protected N‐methyl β‐amino acids derived from the 20 common α‐amino acids. These compounds were prepared in yields of 23–57% (relative to N‐methyl α‐amino acid). In a second approach, twelve N‐protected α‐amino acids could be directly homologated by the Arndt–Eistert procedure, and the resulting β‐amino acids were converted to the 1,3‐oxazinan‐6‐ones in 30–45% yield. Finally, reductive cleavage afforded the desired N‐methyl β‐amino acids in 41–63% yield. One sterically congested β‐amino acid, 3‐methyl‐3‐aminobutanoic acid, did give a high yield (95%) of the 1,3‐oxazinan‐6‐one ( 65 ), and subsequent reductive cleavage gave the corresponding AIBN‐derived N‐methyl β‐amino acid 61 in 71% yield (Scheme 2). Thus, our protocols allow the ready preparation of all N‐methyl β‐amino acids derived from the 20 proteinogenic α‐amino acids.     

Studies on 4‐Thiazolidinones: Scope of the Reactions of 3‐Aryl‐2‐thioxo‐1,3‐thiazolidin‐4‐ones with Cyanide and Cyanate Ions

Treatment of 3‐aryl‐2‐thioxo‐1,3‐thiazolidin‐4‐ones 1 with CN^? and NCO^? effected the ring cleavage providing [(cyanocarbonothioyl)amino]benzenes 4 and arylisothiocyanates 5 , respectively. Similar treatment of 5‐(2‐aryl‐2‐oxoethyl) derivatives 2 afforded 2,4‐bis(2‐aryl‐2‐oxoethylidene)cyclobutane‐1,3‐diones 6 along with each of the preceding products. Treatment of the respective (E,Z)‐5‐(2‐aryl‐2‐oxoethylidene) analogues 3b and 3c with CN^? gave 4b and 4c and 2‐(arylcarbonyl)‐2‐methoxy‐4‐oxopentanedinitriles 7b and 7c , in addition to 3,6‐bis[2‐(4‐chlorophenyl)‐1‐methoxy‐2‐oxoethylidene]‐1,4‐dithiane‐2,5‐dione 8c , which has been generated from 3c . Reactions of 3c or 3d with NCO^? provided 5c or 5d , together with 8c or 8d as pure isomers. In the formation of the MeO products 7 and 8 , the solvent (MeOH) has participated. Structures of these products are based on microanalytical and spectroscopic data. Rationalizations for the above transformations are given.     

Cocrystals of 1,4‐diethynylbenzene with 1,3‐diacetylbenzene and benzene‐1,4‐dicarbaldehyde exhibiting strong nonconventional alkyne–carbonyl C—H…O hydrogen bonds between the components

Weak interactions between organic molecules are important in solid‐state structures where the sum of the weaker interactions support the overall three‐dimensional crystal structure. The sp‐C—H…N hydrogen‐bonding interaction is strong enough to promote the deliberate cocrystallization of a series of diynes with a series of dipyridines. It is also possible that a similar series of cocrystals could be formed between molecules containing a terminal alkyne and molecules which contain carbonyl O atoms as the potential hydrogen‐bond acceptor. I now report the crystal structure of two cocrystals that support this hypothesis. The 1:1 cocrystal of 1,4‐diethynylbenzene with 1,3‐diacetylbenzene, C₁₀H₆·C₁₀H₁₀O₂, (1), and the 1:1 cocrystal of 1,4‐diethynylbenzene with benzene‐1,4‐dicarbaldehyde, C₁₀H₆·C₈H₆O₂, (2), are presented. In both cocrystals, a strong nonconventional ethynyl–carbonyl sp‐C—H…O hydrogen bond is observed between the components. In cocrystal (1), the C—H…O hydrogen‐bond angle is 171.8 (16)° and the H…O and C…O hydrogen‐bond distances are 2.200 (19) and 3.139 (2) Å, respectively. In cocrystal (2), the C—H…O hydrogen‐bond angle is 172.5 (16)° and the H…O and C…O hydrogen‐bond distances are 2.25 (2) and 3.203 (2) Å, respectively.     

ZrCl4/TMSCl as an Efficient Catalyst for Synthesis of 4,6‐Substituted 2‐Alkylthio‐6H‐1,3‐thiazines

4,6‐Substituted‐2‐alkylthio‐6H‐1,3‐thiazines were synthesized by the reaction of S‐alkyl dithiocarbamates and α, β‐unsaturated ketones in the presence of ZrCl₄/TMSCl. The procedure is simple and efficient and gives good to high yields of products.     

Enantio‐ and Diastereoselective Synthesis of Homopropargyl Amines by Copper‐Catalyzed Coupling of Imines, 1,3‐Enynes,and Diborons

An efficient, enantio‐ and diastereoselective, copper‐catalyzed coupling of imines, 1,3‐enynes, and diborons is reported. The process shows broad substrate scope and delivers complex, chiral homopropargyl amines; useful building blocks on the way to biologically‐relevant compounds. In particular, functionalized homopropargyl amines bearing up to three contiguous stereocenters can be prepared in a single step.     

Palladium‐ and Solvent‐Free Synthesis of Ynones by Copper(I)‐Catalyzed Acylation of Terminal Alkynes with Acyl Chlorides under Aerobic Conditions

Air‐stable Cu^I/cryptand‐22 complex was found to be a highly active catalyst for the solvent‐free cross‐coupling reaction of terminal alkynes with different acyl chlorides in the presence of Et₃N as base to give the corresponding ynones in quantitative yields.     

Polymerization of (E)‐1,3‐Pentadiene and (E)‐2‐methyl‐1,3‐pentadiene with neodymium catalysts: Examination of the factors that affect the stereoselectivity

(E)‐1,3‐Pentadiene (EP) and (E)‐2‐methyl‐1,3‐pentadiene (2MP) were polymerized to cis‐1,4 polymers with homogeneous and heterogeneous neodymium catalysts to examine the influence of the physical state of the catalyst on the polymerization stereoselectivity. Data on the polymerization of (E)‐1,3‐hexadiene (EH) are also reported. EP and EH gave cis‐1,4 isotactic polymers both with the homogeneous and with the heterogeneous system, whereas 2MP gave an isotactic cis‐1,4 polymer with the heterogeneous catalyst and a syndiotactic cis‐1,4 polymer, never reported earlier, with the homogeneous one. For comparison, the results obtained with the soluble CpTiCl₃‐based catalyst (Cp = cyclopentadienyl), which gives cis‐1,4 isotactic poly(2MP), are examined. A tentative interpretation is given for the mechanism of the formation of the stereoregular polymers obtained and a complete NMR characterization of the cis‐1,4‐syndiotactic poly(2MP) is reported. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3227–3232     

Copper‐Catalyzed Tandem Synthesis of Functionalized Sulfonyl‐yn‐imines from Sodium Arylsulfinates,Trichloroacetonitrile, and Terminal Alkynes

A one‐pot synthesis of functionalized sulfonyl‐yn‐imines via a Cu‐catalyzed tandem reaction of sodium arylsulfinates, trichloroacetonitrile, and terminal alkynes has been developed.     

Synthesis,psychotropic and anticancer activity of 2,2‐dimethyl‐5‐[5′‐trialkylgermyl(silyl)‐2′‐hetarylidene]‐1,3‐dioxane‐4,6‐diones and their analogues

A series of 2,2‐dimethyl‐5‐(5′‐R‐hetarylidene)‐1,3‐dioxane‐4,6‐diones has been synthesized for examing a structure–activity relationship. Furyl and thienyl derivatives of Meldrum's acid possess neurotropic activity comprising both depriming and activating components. Comparison of acute toxicity of carbon, silicon and germanium analogues in the furan series of the compounds has demonstrated that the germanium derivative is 11.5 times less toxic than the carbon analogue and four times less toxic than the silicon derivative. 2,2‐Dimethyl‐5‐(5′‐triethylsilyl‐2′‐thenylidene)‐1,3‐dioxane‐4,6‐dione has moderate toxicity with the highest neurotropic and cytotoxic activity Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis of 1,3,4‐Oxadiazoles and 1,3‐Thiazolidinones Containing 1,4,5,6‐Tetrahydro‐6‐pyridazinone

The reaction of 1,4,5,6‐tetrahydro‐6‐pyridazinone‐3‐carboxylic acid hydrazides ( 1 ) with aromatic aldehydes afforded 1,4,5,6‐tetrahydro‐6‐pyridazinone‐3‐carbonyl aromatic aldehyde hydrazones ( 2a‐2g ). Heterocyclic derivatives linked 1,3,4‐oxadiazole obtained by cyclocondensation of 2a‐2g with acetic anhydride in absolute ethanol, and 2a‐2g cyclized with mercaptoacetic acid in DMF in the presence of anhydrous ZnCl₂ afforded the 1,3‐thiazolidinone derivatives. The structures of the new compounds were established by elemental analyses, IR, ¹H NMR and MS spectral data.     

CuO‐CeO2 Nanocomposite: A Highly Efficient Recyclable Catalyst for the Green Synthesis of 1,8‐Dioxooctahydroxanthenes in Water

CuO‐CeO₂ nanocomposite is reported as a highly efficient and recyclable catalyst for the green synthesis of 1,8‐dioxooctahydroxanthenes in water. This catalyst can be recovered by simple filtration and recycled up to 8 consecutive runs without any losing of its efficiency.     

New biodegradable polymers from renewable sources: Polyester‐carbonates based on 1,3‐propylene‐co‐1,4‐cyclohexanedimethylene succinate

α,ω‐Dihydroxy‐terminated copolymeric oligomers of a 1,3‐propylene/1,4‐cyclohexanedimethylene succinate structure were obtained by the thermal polycondensation of 1,3‐propanediol/1,4‐cyclohexanedimethanol/succinic acid mixtures. They were subsequently chain‐extended via phosgene synthesis to high molecular weight aliphatic/alicyclic copolyester‐carbonates. These new polymers, besides having a biodegradable backbone, originate from two monomers, namely, 1,3‐propanediol and succinic acid, which can be obtained by renewable sources. Therefore, they have a potential as environmentally friendly materials. All synthesized materials were characterized in reference to their molecular structure by ¹H NMR and ¹³C NMR. Their molecular weights and molecular weight distributions were determined by size exclusion chromatography, and their main thermal properties were measured by DSC. Spectroscopic characterizations were in full agreement with the proposed structures. 1,4‐Cyclohexanedimethanol was used as a diol comonomer to improve the overall thermal properties of poly(1,3‐propylene succinate). The results of the characterization performed show that the initial expectations were only partially satisfied. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2508–2519, 2001     

Copper(II) and Manganese(II) Coordination Polymers of 5‐Aminobenzene‐1,3‐dicarboxylic Acid (abdc) Ligand,Structural Studies of [Cu(μ4‐abdc) (DMF)]n and {[Mn(μ4‐abdc)(H2O)]·H2O}n

Two new two‐dimensional Cu^II and Mn^II coordination polymers of 5‐aminobenzene‐1,3‐dicarboxylic acid (abdc) ligand, [Cu(μ₄‐abdc)(DMF)]_n and {[Mn(μ₄‐abdc)(H₂O)]·H₂O}_n, have been synthesized and characterized by elemental analysis and IR‐ spectroscopy. The single crystal X‐ray analyses show that the coordination number in these complexes is six, CuO₅Cu and MnO₅N. The compounds are structurally diverse and the coordination polymer obtained from copper show significant copper–copper interaction while the manganese coordination polymer shows Mn–N_amino bond.