A practical synthesis of 2‐aminobenzothiazoles via copper(I)‐catalyzed tandem reaction of 2‐iodoanilines with isothiocyanates in ionic liquids

A copper(I)‐catalyzed tandem reaction of 2‐iodoanilines with isothiocyanates was achieved in hydrophobic [bmim][PF₆] ionic liquid under mild conditions, generating a variety of 2‐aminobenzothiazoles in good to excellent yields. The tandem reaction that was carried out in [bmim][PF₆] has some obvious advantages such as accelerated reaction rate and increased yield as compared with the reaction run in volatile solvents such as toluene. Furthermore, the CuI/1,10‐phenanthroline catalytic system can be reused up to eight times without loss of activity and efficiency. Copyright © 2016 John Wiley & Sons, Ltd.     

Postsynthetic modification of IRMOF‐3 with a copper iminopyridine complex as heterogeneous catalyst for the synthesis of 2‐aminobenzothiazoles

A copper iminopyridine complex has been immobilized on to a metal–organic framework (MOF) through postsynthetic modification of IRMOF‐3. The modified MOFs were fully demonstrated by using a variety of methods, and the structural integrity of the modified MOFs has been confirmed by powder X‐ray diffraction (XRD). Furthermore, it was shown that the modified IRMOF‐3 can act as an efficient solid catalyst for the synthesis of 2‐aminobenzothiazoles via the reaction of 2‐iodoanilines with isothiocyanates in a heterogeneous manner. Moreover, the catalyst could be facilely separated from the reaction mixture and reused for six consecutive cycles without significant degradation in catalytic activity. Copyright © 2014 John Wiley & Sons, Ltd.     

Isocyanide‐Based Three‐Component Synthesis of Highly Substituted 1,6‐Dihydro‐6,6‐dimethylpyrazine‐2,3‐dicarbonitrile, 3,4‐Dihydrobenzo[g]quinoxalin‐2‐amine,and 3,4‐Dihydro‐3,3‐dimethyl‐quinoxalin‐2‐amine Derivatives

A novel and efficient isocyanide‐based multicomponent reaction between alkyl or aryl isocyanides 1 , 2,3‐diaminomaleonitrile ( 2 ), naphthalene‐2,3‐diamines ( 6 ) or benzene‐1,2‐diamine ( 9 ), and 3‐oxopentanedioic acid ( 3 ) or Meldrum's acid ( 4 ) or ketones 7 was developed for the ecologic synthesis, at room temperature under mild conditions, of 1,6‐dihydropyrazine‐2,3‐dicarbonitriles 5a – 5f in H₂O without using any catalyst, and of 3,4‐dihydrobenzo[g]quinoxalin‐2‐amine and 3,4‐dihydro‐3,3‐dimethyl‐quinoxalin‐2‐amine derivatives 8a – 8g and 10a – 10e , respectively, in the presence of a catalytic amount of p‐toluenesulfonic acid (TsOH) in EtOH, in good to excellent yields (Scheme 1).     

A Stereoselective Aldol Approach for the Total Syntheses of Two 6‐Alkylated 2H‐Pyran‐2‐ones

A simple and highly efficient stereoselective total synthesis of the 6‐alkylated pyranones (6R)‐6‐[(1E,4R,6R)‐4,6‐dihydroxy‐10‐phenyldec‐1‐en‐1‐yl]‐5,6‐dihydro‐2H‐pyran‐2‐one ( 1 ) and (6S)‐5,6‐dihydro‐6‐[(2R)‐2‐hydroxy‐6‐phenylhexyl]‐2H‐pyran‐2‐one ( 2 ) was developed using Crimmins' aldol reaction, SmI₂ reduction, Grubbs‐II‐catalyzed olefin cross‐metathesis, and Still's modified Horner? Wadsworth? Emmons reaction.     

Synthesis of 4‐((2‐hydroxynaphthalen‐1‐yl)(aryl)methyl)‐5‐methyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐ones using nano‐Zn‐[2‐boromophenyl‐salicylaldimine‐methylpyranopyrazole]Cl2 nanoparticles

Nano‐Zn‐[2‐boromophenyl‐salicylaldimine‐methylpyranopyrazole]Cl₂ (nano‐[Zn‐2BSMP]Cl₂) as a nanoparticle Schiff base complex and a catalyst was introduced for the solvent‐free synthesis of 4‐((2‐hydroxynaphthalen‐1‐yl)(aryl)methyl)‐5‐methyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐ones by the multicomponent condensation reaction of various aromatic aldehydes, β‐naphthol, ethyl acetoacetate, and phenyl hydrazine at room temperature.     

The Stereoselective Total Synthesis of (6S)‐5,6‐Dihydro‐6‐[(2R)‐2‐hydroxy‐6‐phenylhexyl]‐2H‐pyran‐2‐one via Prins Cyclization

The stereoselective total synthesis of an antiproliferative and antifungal α‐pyrone natural product (6S)‐5,6‐dihydro‐6‐[(2R)‐2‐hydroxy‐6‐phenylhexyl]‐2H‐pyran‐2‐one is described. The key steps involved are the Prins cyclization, Mitsunobu reaction, and ring‐closing metathesis reaction.     

Ultrasound‐Assisted Wittig Reaction: A Short,Efficient Synthesis of 2‐Methoxy‐6‐Alkyl‐1,4‐Benzoquinones

A short, efficient synthesis of 2‐methoxy‐6‐alkyl‐1,4‐benzoquinones is described. Ultrasound‐assisted Wittig reaction of alkyltriphenyl phosphonium bromides with o‐vanillin in basic aqueous conditions followed by reduction with Na/n‐BuOH gave 2‐methoxy‐6‐alkylphenols. Oxidation of 2‐methoxy‐6‐alkylphenols with Fremy's salt produced the title compounds.     

Copper(II)‐Catalyzed Synthesis of N‐Substituted‐3‐amino‐4‐cyano‐isoquinoline‐1(2H)‐ones by the Reaction of N‐Substituted‐2‐iodobenzamides with Malononitrile

A novel Cu(OAc)₂·H₂O catalyzed coupling reaction of N‐substituted‐2‐iodobenzamides with malononitrile to afford N‐substituted‐3‐amino‐4‐cyano‐isoquinoline‐1(2H)‐ones is described. The reaction proceeded in DMSO at 90°C for 5 h in nitrogen without external ligands.     

Synthesis,structure and cytotoxicity of new 2‐[(3‐aminopropyl)dimethylsilyl]‐5‐furfural diethylacetals and 2‐[(3‐aminopropyl)dimethylsilyl]‐5‐phenylfurans

Novel 2‐[(3‐aminopropyl)dimethylsilyl]‐5‐furfural diethylacetals and 2‐[(3‐aminopropyl)di‐methylsilyl]‐5‐phenylfurans have been synthesized by a hydrosilylation reaction of aliphatic and heterocyclic N‐allylamines in the presence of the Speier's catalyst. The effects of the structure of the amine and nature of organic substituent at the furan ring on the cytotoxicity of the new compounds have been studied. Copyright © 2013 John Wiley & Sons, Ltd.     

Study on the Color Reaction of Silver with 2‐(2‐Quinolylazo)‐5‐Dimethylaminoaniline and its Application

A new chromogenic reagent, 2‐(2‐quinolylazo)‐5‐dimethylaminoaniline (QADMAA) was synthesized. A highly sensitive, selective and rapid method for the determination of silver based on the rapid reaction of silver(I) with QADMAA was developed. In the presence of pH = 6.5 sodium citrate‐sodium hydroxide buffer solution and sodium dodecyl sulfonate (SDS) medium, QADMAA reacts with silver to form a violet complex of a molar ratio 1:2 (silver to QADMAA). The molar absorptivity of the complex is 1.26 × 10⁵ L. mol^?1.cm^?1 at 570 nm. Beer's law is obeyed in the range of 0.01–0.6 μg/mL. The relative standard deviation for eleven replicate samples of 0.2 μg/mL silver is 1.76%. This method was applied to the determination of silver in water with good results.     

Copper(II)‐Catalyzed Tandem Synthesis of Substituted 3‐Methyleneisoindolin‐1‐ones

An efficient strategy for the synthesis of a variety of 3‐methyleneisoindolin‐1‐ones has been developed. The reaction proceeded from coupling of 2‐iodobenzamides (or 2‐bromobenzamides) and terminal alkynes via Cu(OAc)₂·H₂O/2,2′‐biimidazole catalyzed in DMF at 60°C and subsequent additive cyclization produced substituted 3‐methyleneisoindolin‐1‐ones in good to excellent yields.     

Synthesis and Crystal Structure of 3,3,6,6‐Tetramethylmorpholine‐2,5‐dione,and Its 5‐Monothioxo and 2,5‐Dithioxo Derivatives

The synthesis of 3,3‐dimethylmorpholine‐2,5‐diones 4a was achieved conveniently via the ‘direct amide cyclization’ of the linear precursors of type 3 , which were prepared by coupling of 2,2‐dimethyl‐2H‐azirin‐3‐amines 2 with 2‐hydroxyalkanoic acids 1 . Thionation of 4a with Lawesson's reagent yielded the corresponding 5‐thioxomorpholin‐2‐ones 10 and morpholine‐2,5‐dithiones 11 , respectively, depending on the reaction conditions. The structures of 3aa, 4aa, 10a , and 11a were established by X‐ray crystallography. All attempts to prepare S‐containing morpholine‐2,5‐dione analogs or thiomorpholine‐2,5‐diones by cyclization of corresponding S‐containing precursors were unsuccessful and led to various other products. The structures of some of them have also been established by X‐ray crystallography.     

Two‐Step Synthesis of 1,3‐Disubstituted 3,4‐Dihydro‐4‐thioxoquinazolin‐2(1H)‐ones from 1‐Bromo‐2‐fluorobenzenes

An efficient synthesis of 3‐alkyl‐3,4‐dihydro‐4‐thioxobenzoquinazolin‐2(1H)‐ones 3 has been accomplished in two steps and in satisfactory yields from 1‐bromo‐2‐fluorobenzenes 1 . Thus, the reaction of 1‐fluoro‐2‐lithiobenzenes, generated by the Br/Li exchange between 1 and BuLi, with alkyl isothiocyanates, gives N‐alkyl‐2‐fluorobenzothioamides 2 , which, in turn, react with a series of isocyanates in the presence of NaH to give the desired products 3 .     

A Novel and Efficient Synthesis of 3‐[(4,5‐Dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐chromen‐2‐ones (=3‐[(4,5‐Dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐1‐benzopyran‐2‐ones)

An efficient one‐pot synthesis of 3‐[(4,5‐dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐chromen‐2‐one (=3‐[(4,5‐dihydro‐1H‐pyrrol‐3yl)carbonyl]‐2H‐1‐benzopyran‐2‐one) derivatives 4 by a four‐component reaction of a salicylaldehyde 1 , 4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one, a benzylamine 2 , and a diaroylacetylene (=1,4‐diarylbut‐2‐yne‐1,4‐dione) 3 in EtOH is reported. This new protocol has the advantages of high yields (Table), and convenient operation. The structures of these coumarin (=2H‐1‐benzopyran‐2‐one) derivatives, which are important compounds in organic chemistry, were confirmed spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this reaction is proposed (Scheme 2).     

Synthesis and properties of gradient copolymers based on 2‐phenyl‐2‐oxazoline and 2‐nonyl‐2‐oxazoline

In this study, the structure–property relationships for a series of statistical 2‐nonyl‐2‐oxazoline (NonOx) and 2‐phenyl‐2‐oxazoline (PhOx) copolymers were investigated for the first time. The copolymerization kinetics were studied and the reactivity ratios were calculated to be r_NonOx = 7.1 ± 1.4 and r_PhOx = 0.02 ± 0.1 revealing the formation of gradient copolymers. The synthesis of a systematical series of NonOx–PhOx copolymers is described, whereby the amount of NonOx was increased in steps of 10 mol %. The thermal and surface properties were investigated for this series of well‐defined copolymers. The thermal properties revealed a linear decrease in glass transition temperature for copolymers containing up to 39 wt % NonOx. Furthermore, the melting temperature of the copolymers containing 0 to 55 wt % PhOx linearly decreased most likely due to disturbance of the NonOx crystalline domains by incorporation of PhOx in the NonOx part of the copolymer. The surface energies of spincoated polymer films revealed a strong decrease in surface energy upon incorporation of NonOx in the copolymers due to strong phase separation between NonOx and PhOx allowing the NonOx chains to orient to the surface. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6433–6440, 2009     

Microwave Accelerated Polymerization of 2‐Phenyl‐2‐oxazoline

Summary: We studied the cationic ring‐opening polymerization of 2‐phenyl‐2‐oxazoline under microwave irradiation. A comparison with thermal heating shows a great enhancement in the reaction rates while the living character of the polymerization is conserved. The polymerizations were performed at the temperature of boiling butyronitrile (123 °C). The polymerization of 2‐phenyl‐2‐oxazoline under microwave conditions, described herein for the first time, is shown to be a rapid and environmentally friendly alternative to the classical methods.

Schematic of the activation of the reactive site by microwave irradiation.     

A Convenient Synthesis of 2,3‐Dihydro‐3‐methylidene‐1H‐isoindol‐1‐ones by Reaction of 2‐Formylbenzo­nitriles with Dimethyloxosulfonium Methylide

A facile method for the synthesis of 2,3‐dihydro‐3‐methylidene‐1H‐isoindol‐1‐one and its derivatives carrying substituent(s) at C(5) and/or C(6) has been developed. The reaction of 2‐formylbenzonitrile ( 1a ) with dimethyloxosulfonium methylide, generated by the treatment of trimethylsulfoxonium iodide with NaH in DMSO/THF at 0°, resulted in the formation of 2,3‐dihydro‐3‐methylidene‐1H‐isoindol‐1‐one ( 2a ) in 77% yield. Similarly, six 2‐formylbenzonitriles carrying substituent(s) at C(4) and/or C(5), i.e., 1b – 1g , also gave the corresponding expected products 2b – 2g in comparable yields.     

Living tert‐butyllithium initiated anionic polymerization of 2‐vinylnaphthalene in toluene‐tetrahydrofuran mixtures

The tert‐butyllithium (t‐BuLi) initiated polymerization of carefully purified 2‐vinylnaphthalene in toluene containing small amounts of tetrahydrofuran with respect to t‐BuLi proceeds on a timescale of several hours without significant deactivation and allows the synthesis of very narrow molecular weight distribution poly‐(2‐vinylnaphthalene) (P2VN) (polydispersities as low as 1.04) and molecular weights between 1000 and 20,000. The absence of P2VN‐Li deactivation at these conditions is also indicated by high degrees of trimethylsilyl end functionalization (>95%) and coupling with dibromoxylene. The respective polymerizations of conventionally purified monomer reveal a complex polymerization profile consistent with deactivation by 2‐acetylnaphthalene during the early stages of the reaction. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3034–3041, 2001     

1‐(α‐Aminobenzyl)‐2‐naphthol as phosphine‐free ligand for Pd‐catalyzed Suzuki and one‐pot Wittig‐Suzuki reaction

Air stable and easily accessible, 1‐(α‐aminobenzyl)‐2‐naphthols are used as efficient phosphine‐free ligands in palladium‐catalyzed Suzuki reaction for a variety of substrates under conventional heating as well as ultrasonic conditions. Multi‐brominated aromatic substrates were successfully converted to corresponding arylated moieties with good conversion and selectivity. A novel one‐pot two‐step cascade reaction strategy involving Wittig and Suzuki reactions is developed for efficient synthesis of 4‐styryl biphenyls (C₆‐C₂‐C₆‐C₆ unit). Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis of (+) or (-)-2-(8′-Diphenylphosphino-1′-naphthyl)oxazoline Ligands and Their Application in Pd-Catalyzed Allylic Alkylation Reaction

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