N‐Bromosuccinimide (NBS): A Novel and Efficient Catalyst for the Synthesis of 14‐Aryl‐14H‐dibenzo[a,j]xanthenes under Solvent‐Free Conditions

A novel procedure for the synthesis of 14‐aryl‐14H‐dibenzo[a,j]xanthenes through one‐pot condensation of naphthalen‐2‐ol with arenecarbaldehydes in the presence of N‐bromosuccinimide (NBS) as catalyst under solvent‐free conditions is described.     

Nucleophilic Substitution on Porphyrin Ring： Synthesis of 2-（2-Hydroxynaphthyl）-5,10,15,20-tetraphenylporphyrin

The reactions of 2-nitro-5,10,15,20-tetraphenylporphyrin （1） and its Ni （Ⅱ） （2）, Cu （Ⅱ） （3）, Zn （Ⅱ） （4） complexes with sodium 2-naphthoxide have been investigated in different solvents for preparing 2-substituted porphyrins. 2-（2-Hydroxynaphthyl）-5,10,15,20-tetraphenyl porphyrin （5） and its Ni （Ⅱ） （6）, Cu （Ⅱ） （7）, Zn （Ⅱ） （8） complexes were obtained in 72%, 78%, 81% and 65% yields in 2-naphthol at 150 ℃ respectively. The same products were also obtained in other protic solvents such as diglycol and diglycol monomethyl ether. When the reactions proceeded in aprotic solvent DMF at 150 ℃, besides 5 （70%）, 6 （34%）, 7 （54%） and 8 （50%）, the corresponding 2-（2-naphythoxy）-5, 10,15,20-tetraphenylporphyrin （9）, and its Ni （Ⅱ） （10）, Cu （Ⅱ） （11）, Zn （Ⅱ） （12） complexes were also obtained in minor, 40%, 18% and 2% yields respectively, but only 5, 6, 7, 8 were found at room temperature in DMF or DMSO. These reactions axe much faster than those of 1-4 with sodium phenoxide. The formation of C-coupling products 5-8 was proposed via SRN 1 mechanism.     

Synthesis of Imidazo[1,2‐a]pyridines Using Fe3O4@SiO2 as an Efficient Nanomagnetic Catalyst via a One‐Pot Multicomponent Reaction

A one‐pot multicomponent synthesis of imidazo[1,2‐a]pyridine derivatives by using pyridin‐2‐amines, aldehydes, and terminal alkynes in the presence of a catalytic amount of silica‐supported iron oxide (Fe₃O₄@SiO₂) nanoparticles in refluxing EtOH in good‐to‐excellent yields is reported.     

Efficient Synthesis of Oxazolidin‐2‐one via (Chitosan‐Schiff Base)cobalt(II)‐Catalyzed Oxidative Carbonylation of 2‐Aminoalkan‐1‐ols

The (chitosan‐Schiff base)cobalt(II) complex was found to be an efficient catalyst for the oxidative carbonylation (CO/O₂) of 2‐aminoalkan‐1‐ols 1 to give oxazolidin‐2‐ones 2 , in the presence of NaI. The effects of promoters, temperature, solvents, and other reaction conditions were investigated in this study.     

TiO2 as a Reusable Catalyst for the One‐Pot Synthesis of 3,4‐Dihydropyrimidin‐2(1H)‐ones under Solvent‐Free Conditions

An efficient solvent‐free method for the synthesis of various 3,4‐dihydropyrimidin‐2(1H)‐ones using TiO₂ as a recyclable heterogeneous catalyst is described. Compared to known methods, satisfactory results are obtained with excellent yields, short reaction times, and simplicity in the experimental procedure.     

Synthesis of Some New 2‐Oxo‐N‐[(10H‐phenothiazin‐10‐yl)alkyl] Derivatives of Azetidine‐1‐carboxamides

The synthesis of a new series of 4‐aryl‐3‐chloro‐2‐oxo‐N‐[3‐(10H‐phenothiazin‐10‐yl)propyl]azetidine‐1‐carboxamides, 4a – 4m , is described. Phenothiazine on reaction with Cl(CH₂)₃Br at room temperature gave 10‐(3‐chloropropyl)‐10H‐phenothiazine ( 1 ), and the latter reacted with urea to yield 1‐[3‐(10H‐phenothiazin‐10‐yl)propyl]urea ( 2 ). Further reaction of 2 with several substituted aromatic aldehydes led to N‐(arylmethylidene)‐N′‐[3‐(phenothiazin‐10‐yl)propyl]ureas 3a – 3m , which, on treatment with ClCH₂COCl in the presence of Et₃N, furnished the desired racemic trans‐2‐oxoazetidin‐1‐carboxamide derivatives 4a – 4m . The structures of all new compounds were confirmed by IR, and ¹H‐ and ¹³C‐NMR spectroscopy, FAB mass spectrometry, and chemical methods.     

An Efficient and Odorless Synthesis of Thioethers Using 2‐[Bis(alkylthio)methylene]‐3‐oxo‐N‐o‐tolylbutanamides as Thiol Equivalents

Using 2‐[bis(alkylthio)methylene]‐3‐oxo‐N‐o‐tolylbutanamides 1 as odorless thiol equivalents, an efficient and odorless synthesis of thioethers has been developed. Promoted by NaOH in EtOH, the cleavage of 1 commences to generate thiolate anions, and the generated thiolate anions then react with halides to give various thioethers in good yield. It is noteworthy that only a very faint odor of thiols can be perceived during both the reaction and the workup.     

HClO4‐SiO2: An Efficient and Useful Catalyst for the Synthesis of 3‐Aryl‐2H‐benzo[1,4]oxazine

HClO₄‐SiO₂, efficiently catalyzed the condensation of o‐aminophenols and 2‐bromo‐1‐aryl‐ethanones to yield 3‐aryl‐2H‐benzo[1,4]oxazines in good yields.     

Zirconyl Chloride (= Dichlorooxozirconium) as an Efficient Catalyst for One‐Pot Multicomponent Synthesis of Homoallylic Amines

Zirconyl chloride (ZrOCl₂) catalyzes efficiently the one‐pot three component reactions of aldehydes, amines, and allyltributylstannane at room temperature to furnish the corresponding homoallylic amines in short reaction times and in excellent yields.     

Phosphomolybdic Acid (PMA)–SiO2 as a Heterogeneous Solid Acid Catalyst for the One‐Pot Synthesis of 2H‐Indazolo[1,2‐b]phthalazine‐triones

Phosphomolybdic acid (PMA)–SiO₂ was found to be an efficient catalyst for the three‐component condensation reaction of phthalhydrazide, 1,3‐diketone, and aldehydes to produce 2H‐indazolo[1,2‐b]phthalazine‐triones in excellent yields. The catalyst can be recovered and reused without significant loss of activity.     

Synthesis of 2,3‐Diaryl‐3H‐pyrrolo[2,3‐c]pyridin‐3‐ol Derivatives by the Reaction of Aryl(3‐isocyanopyridin‐4‐yl)methanones with Aryl Grignard Reagents

The reaction of aryl(3‐isocyanopyridin‐4‐yl)methanones 1 , easily prepared from commercially available pyridin‐3‐amine, with aryl Grignard reagents gave, after aqueous workup, 2,3‐diaryl‐3H‐pyrrolo[2,3‐c]pyridin‐3‐ols 2 . These rather unstable alcohols were O‐acylated with Ac₂O in pyridine in the presence of a catalytic amount of 4‐(dimethylamino)pyridine (DMAP) to afford the corresponding 2,3‐diaryl‐3H‐pyrrolo[2,3‐c]pyridin‐3‐yl acetates 3 in relatively good yields.     

Synthesis of 1‐Acyl‐3,4‐dihydroquinazoline‐2(1H)‐thiones by Cyclization of N‐[2‐(Isothiocyanatomethyl)phenyl] Amides Generated in situ from N‐[2‐(Azidomethyl)phenyl] Amides

An efficient method for the preparation of 1‐acyl‐3,4‐dihydroquinazoline‐2(1H)‐thiones 5 has been developed. The reaction of N‐[2‐(azidomethyl)phenyl] amides 3 , easily prepared by a three‐step sequence starting with (2‐aminophenyl)methanols, with Ph₃P, followed by CS₂, allowed generation of N‐[2‐(isothiocyanatomethyl)phenyl]‐amide intermediates 4 , which underwent cyclization on treatment with NaH to furnish the corresponding desired products in generally good yields.     

One‐Pot Synthesis of 3‐Acetyl‐2‐aryl‐3,4‐dihydroquinazolines from N‐[2‐(Azidomethyl)phenyl]benzamides Utilizing Intramolecular Aza‐Wittig Reaction

A new and convenient method for the preparation of 3,4‐dihydroquinazolines 5 with aryl and Ac groups at C(2) and N(3), respectively, has been developed. The key sequence is the formation of aza‐phosphorane intermediates by the reaction of N‐[2‐(azidomethyl)phenyl]benzamides 1 with Ph₃P, followed by intramolecular aza‐Wittig reaction and 3‐acetylation, which can be conducted in one‐pot.     

Synthesis of 14‐{[(Un)substituted phenyl] or alkyl}‐14H‐dibenzo[a,j]xanthenes Using Yb(OTf)3 as an Efficient Catalyst under Solvent‐free Conditions

A series of 14‐{[(Un)substituted phenyl] or alkyl}‐14H‐dibenzo[a,j]xanthenes were prepared under solvent‐free conditions by Yb(OTf)₃ catalyzed condensation reactions of β‐naphthol with various aldehydes. The process presented here is operationally simple, environmentally benign and has good to excellent yields. Furthermore, the catalyst can be recovered conveniently and reused efficiently.     

Solvent‐free Thia‐Michael Addition Reactions Using 3‐[Bis(alkylthio)methylene]pentane‐2,4‐diones as Efficient and Odorless Thiol Equivalents

本文研究了3-（二烷硫基甲烯基）-2,4-戊二酮1a 和 1b作为无气味硫醇替代物在无溶剂条件下硫杂麦克尔加成反应中的应用。在浓盐酸作用下,化合物1 发生断键反应, 现场产生的硫醇参与a,b-不饱和羰基化合物2的共轭加成反应,高产率地形成了b-羰基硫醚化合物 3.     

Aluminium Nitrate Nonahydrate (Al(NO3)3⋅9 H2O): An Efficient Oxidant Catalyst for the One‐Pot Synthesis of Biginelli Compounds from Benzyl Alcohols

A clean and efficient tandem oxidative cyclocondensation process is reported for the synthesis of 3,4‐dihydropyrimidin‐2(1H)‐one or ‐thione derivatives from primary aryl alcohols, β‐keto esters, and urea or thiourea in the presence of Al(NO₃)₃?9 H₂O as oxidant catalyst (Scheme, Table 5).     

One‐Pot Synthesis of N,N‐Disubstituted (Z)‐4‐(Halomethylidene)‐4H‐3,1‐benzothiazin‐2‐amines from 2‐(2,2‐Dihaloethenyl)phenyl Isothiocyanates and Secondary Amines

We have developed a one‐pot procedure for the preparation of N,N‐disubstituted (Z)‐4‐(halomethylidene)‐4H‐3,1‐benzothiazin‐2‐amines 3 from 2‐(2,2‐dihaloethenyl)phenyl isothiocyanates 1 , easily accessible from known 2‐(2,2‐dihaloethenyl)benzenamines by a three‐step sequence, and secondary amines. Thus, the isothiocyanates 1 react with secondary amines to afford the corresponding thiourea derivatives, of which the treatment with NaH provides the desired products.     

An Efficient One‐pot Access to Substituted Dihydropyrrol‐2‐one Derivatives Using Sucrose as Natural,Biodegradable and Inexpensive Catalyst

An efficient and simple procedure for the synthesis of highly substituted dihydropyrrol‐2‐ones has been developed via one‐pot four‐component condensation of amines, dialkyl acetylenedicarboxyaltes and formaldehyde in the presence of sucrose as an organocatalyst. The salient advantages of this method are using a natural, biodegradable and commercial available catalyst, good yields, short reaction times, simple work‐up and lack of need for column chromatography.