Protease-catalyzed Synthesis of Bz-Arg-Gly-Asp-OMe in Full Aqueous Medium

Synthesis of N-benzoyl-argininylglycylasparagine methyl ester(Bz-Arg-Gly-Asp-OMe),a precursor tripeptide of Arg-Gly-Asp)was catalyzed by papain under kinetic control,at alkaline pH,in a full aqueous medium.The substrates were N-benzoyl-argininylglycine ethyl ester and asparagine dimethyl ester.An aqueous solution of 0.1 mol/L KCl/NaOH containing 8 mmol/L EDTA and 2 mmol/L DTT was selected as the reaction medium.The synthesized hydrophilic tripeptide was soluble in the reaction medium during the reaction process,however,the secondary hydro-lysis of the tripeptide product was not considerable.The effects of different factors,including water content,temperature,reaction time,and molar ratio of the substrates,on the yield of Bz-Arg-Gly-Asp-OMe were examined.The optimal reaction conditions were 0.05 mol/L Bz-Arg-Gly-OEt and 0.15 mol/L Asp(-OMe)2·HCl in 0.1 mol/L KCl/NaOH solution(pH 8.5),at 40 ℃,and a reaction time of 60 min,with a maximum conversion yield of 62.4%.     

Synthesis of 4‐Substituted‐ and 1,4‐Disubstituted‐4‐Hydroxypyrrolidin‐2‐ones

This report describes the synthesis of 4‐substituted‐ and 1,4‐disubstituted‐4‐hydroxypyrrolidin‐2‐ones by cyclization of intermediate γ‐aminoesters prepared from alkylbenzylamines, α‐bromoketones, and lithio ethyl acetate.     

One-Pot Synthesis of 1,2,3-Triazoles using Polymer-Supported Propyne in Aqueous Solution

A practical and efficient liquid-phase synthesis of 1,2,3-triazoles using poly（ethylene glycol） as support in aqueous solution was described. The title compounds, 1,2,3-triazoles 5 were obtained by a one-pot three-component 1,3-dipolar cycloaddition reaction in middle yields. In addition, a series of unexpected products 7 of Sonogashira reaction were also formed under the same condition.     

Sonochemical Degradation of Polychlorinated Biphenyls in Aqueous Solution

Ultrasonic waves in a liquid induce the formation of cavitation bubbles. Submitted to an oscillating pressure field, cavities filled with vapor and dissolved gas pulsate, grow and implode violently when they reach a critical resonant size. According to the 慼ot spot?theory, extremely high temperature and pressure are produced during the collapse of cavitation bubbles1. Under these extreme conditions, the molecules vaporized in the bubbles as well as in the surrounding condensed layer could …     

Three‐Component One‐Pot Synthesis of 1,4‐Dihydropyrano[2,3‐c]pyrazole Derivatives in Aqueous Media

Abstract

6‐Amino‐5‐cyano‐4‐aryl‐1,4‐dihydropyrano[2,3‐c]pyrazoles were synthesized by three‐component reaction of aromatic aldehydes, malononitrile, and 3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one using triethylbenzylammonium chloride (TEBA) as catalyst in aqueous media. The reaction has the advantages of good yield, less pollution, ease of separation, and of being environment friendly.     

Microwave Assisted Synthesis of Fluorinated Hexahydro 1,3,5‐Triazine Derivatives in Aqueous Medium and One Pot Synthesis of 1,2,4‐Triazolo(4,3‐a)1,3,5‐triazines

Abstract

A multi‐component condensation of substituted phenylthiourea/urea, aqueous formaldehyde and substituted aromatic/heterocyclic amines lead to 2‐thioxohexahydro‐1,3,5‐triazines (4) in aqueous medium under microwave irradiation in 30–60 sec in quantitative yield with reasonable purity. Further, triazolo[4,3‐a]triazines were also prepared by a one‐pot reaction of ‘in situ’ synthesized triazinyl hydrazine (7) with CS₂ (9).     

Unexpected Microwave Reaction of 1,3‐Disubstituted Imidazolium Salts: A Novel Synthesis of 1,3‐Disubstituted Imidazole‐2‐thiones

Microwave‐promoted reaction of 1,3‐disubstituted imidazolium salts with potassium thioacetate or potassium thiocyanate under solvent‐free conditions provided a rapid and efficient synthesis of 1,3‐disubstituted imidazole‐2‐thiones.     

Stereoselective Synthesis of 2,6‐Disubstituted Tetrahydropyridines Via Aza‐Diels‐Alder Reactions

Abstract

The aza‐Diels‐Alder reactions of (E)‐2‐(phenylthio)‐1,3‐pentadiene (2) with iminium salts gave the 2,6‐disubstituted tetrahydropyridines 3–8. Factors influencing the stereochemistry and reactivity of these reactions were also studied.     

Convenient Synthesis of Structurally Novel 1,3‐Disubstituted Azetidine Derivatives

A convenient synthesis of structurally novel 1,3‐disubstituted azetidine derivatives is described. The approach involves condensation of an azetidine building block with sulfonylated carbamic acid methyl ester, subsequently followed by quenching the imidoyl chloride with amines. Different derivatives were prepared by substituting benzhydrol as well as benzenesulfonamide as part of the core structure.     

Synthesis of 3‐Aryl‐5‐methyl 4‐Substituted [1,2,4]Triazoles

Treatment of N‐substituted acetamides with oxalyl chloride generates imidoyl chlorides, which react readily with aryl hydrazides. Following cyclization, triazoles can easily be obtained in moderate to good yields. 5‐Methyl triazoles can be further functionalized through α‐lithiation and subsequent reaction with an electrophile.     

One‐Pot Synthesis of 2‐Acylimino‐3‐aryl‐thiazoline Derivatives in Aqueous Media

A one‐pot, two‐step synthesis for acyliminothiazolines by treated N,N′‐substituted thioureas with α‐bromocarbonyl compounds under aqueous media was described. Compared to the classical reaction in organic solvents, this method consistently has the advantage of short reaction times, convenient procedures, and mild reaction conditions.     

Microwave‐Assisted Synthesis of N,N′‐Disubstituted Acetamidine Ligands

Under microwave activation, triethylorthoacetate reacts with the substituted anilines in the presence of acetic acid as a catalyst, producing acetamidine in moderate to high yields. The X‐ray structures of the new amidines, N,N′‐bis(3,5‐dimethylphenyl)‐acetamidine and N,N′‐bis(p‐tolyl)acetamidine, are also reported, revealing polymeric chains supported by intramolecular H‐bonds.     

Clean,One‐Pot Synthesis of Naphthopyran Derivatives in Aqueous Media

A general and practical one‐pot synthesis of naphthopyran derivatives using hexadecyltrimethylammonium bromide (HTMAB) as catalyst (10 mol%) is described. This method provides several advantages such as neutral conditions, high yields and simple workup procedure. The catalyst is low cost, facile, active, environmentally friendly, and reusable. In addition, water is chosen as a green solvent.     

Synthesis of 3,7—Disubstituted 1,4—Benzodiazepin—2—one

A series of 3-methoxycarbonylpropoxy-7-(imidazol-4-ylpropinamide)-1,3-dihydrogen-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-ones,as farnesyltransferase(Ftase) inhibitors,were synthesized. The preparation of the key intermediate,7-amino-3-methoxycabonylpropoxy-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-one,was improved.     

Isocyanide‐Based Multicomponent Synthesis of Functionalized 2,6‐Dioxohexahydropyrimidines in 1 M Aqueous Glucose

An effective route to novel 2,6‐dioxohexahydropyrimidines is described. This involves reaction of alkyl isocyanides and dialkyl acetylenedicarboxylates in the presence of N,N′‐dimethylurea in 1M aq. glucose.     

Synthesis of Novel Asymmetrical 1,4‐Dihydropyridine Derivatives

Asymmetrical 1,4‐dihydropyridine esters 3a and 3i–k were synthesized from the symmetrical precursor 1 through the intermediate 2‐bromomethyl derivative 2. Then, compound 3a was subjected to a different transformation for preparation of 1,4‐dihydropyridine derivatives 3b–h.     

Simple and Efficient One‐Pot Synthesis of 2,4‐Diaryl‐1,2,3‐triazoles

A general and efficient method for the preparation of 2,4‐diaryl‐1,2,3‐triazoles from α‐hydroxyacetophenones and phenylhydrazines is reported. The essential characteristics of this method include mild reaction conditions, a straightforward workup procedure, and comparatively higher yields.     

Regiospecific Synthesis of Disubstituted Pyridin‐2‐ones and Trisubstituted Phenols with Vinamidinium Salts

A highly efficient and versatile method for the synthesis of 3‐acyl‐5‐aryl or arylsulfonylpyridin‐2‐ones and 3‐alkyl‐5‐aryl‐2‐hydroxybenzamides in one step via regiospecific cyclocondensation reaction of β‐keto‐amides with vinamidinium salts is described.     

Cyclodextrins in Polymer Synthesis: Free Radical Polymerization of a tert-Butylmethacrylate-Cyclodextrin Host–Guest System in Aqueous Medium

The homopolymerization of methylated-β-cyclodextrin (me-β-CD) host–guest compound of tert-butyl methacrylate (1a) is described. We investigated the free radical polymerization of the complexed monomer (1a) and of the free monomer (1) at ambient and high temperature. Poly(tert-butylmethacrylate) synthesized via the cyclodextrin mediated method exhibited number-average molecular weights ranging from 12,000–60,000 g/mol with polydispersities from 1.9–3.1. The polymerizations without cyclodextrin show significantly lower yields in comparison with the cyclodextrin mediated polymerizations. Here, the polymer obtained is colloidal dispersed. At ambient temperature (20°C) no polymerization occurs in the absence of cyclodextrin, whereas, under the same conditions, the homopolymerization of the complexed monomer (1a) leads to polymerization with yields around 75%.