Syntheses of acyclic C‐glycosidic derivatives of 1,2,4‐triazoles by cycloadditions of 1‐aza‐2‐azoniaallene salts to D‐glucononitrile‐2,3,4,5,6‐pentaacetate

Reported are preparations of acyclic derivatives of 1,2,4‐triazole‐5‐glycosidies 9 by cycloadditions of 1‐aza‐2‐azonia‐allene salts 3 to the nitrile group of D‐glucononitrile‐2,3,4,5,6‐pentaacetate 5 affording triazolium salts 8 , which with aqueous sodium hydogencarbonate are hydrolyzed to 9 . Deacetylation of compounds 9 produced the C‐glycosides 10 .     

A facile three‐components,one‐pot synthesis of pyrimido[4,5‐d]pyrimidine‐2,5‐dione derivatives under microwave‐assisted conditions

Pyrimido[4,5‐d]pyrimidine‐2,5‐dione derivatives have been synthesized in high yields in a novel, onepot, and efficient process by condensation of 6‐amino‐3‐methyl‐2‐(methylthio)pyrimidin‐4(3H)‐one, aldehydes and urea under microwave‐assisted conditions.     

Synthesis of α‐[5‐(5‐amino‐1,3,4‐thiadiazol‐2‐yl)‐2‐imidazolylthio]acetic acids

The paper describes synthesis and antituberculosis activity of α‐[5‐(5‐amino‐1,3,4‐thiadiazol‐2‐yl)‐imidazol‐2‐ylthio]acetic acids ( 5a,b ). The compounds were tested against Mycobacterium tuberculosis strain H37Rv in comparison to rifampicin. Compounds exhibited low activity (MIC ≤ 6.25 μg/ml, % inhibition ≥ 24).     

A new convenient synthesis of 2,4‐disubstituted‐1,2,4‐triazolo[1,5‐a] quinazolin‐5(4H)‐ones

A novel series of 2,4‐disubstituted‐1,2,4‐triazolo[1,5‐a]quinazolin‐5(4H)‐ones were prepared by Dimroth rearrangement of their respective isomers namely 1,4‐disubstituted‐[1,2,4]triazolo[4,3‐a]‐quinazolin‐5(4H)‐ones. The latter were prepared via new synthetic strategy based on 1,5‐elecrocyclization of the respective N‐(4‐oxo‐3‐phenylquinazolin‐2‐yl)nitrilimines.     

The stereoselective synthesis of e‐1,2‐bis(3‐indolizinyl)ethylenes by the reactions of 3‐thioformylindolizines with n‐tributylphosphine

3‐Thioformylindolizines undergo novel reductive coupling reaction in the presence of tributylphosphine to give E‐1,2‐bis(3‐indolizinyl)ethylenes in high yield. These reactions proceed via (3‐indolizinyl)methylene carbene intermediate and provide a new, stereoselective synthesis of the bis(3‐indolizinyl)ethylene derivatives highly.     

Synthesis of alicyclic N‐substituted 1,3‐amino alcohols via 1,3‐oxazines

Alicyclic N‐substituted 1,3‐amino alcohols 13‐18 were prepared in a facile way in a one‐pot procedure from 1,3‐oxazines 5‐8 in the presence of a ketone 9‐12 . The complex reaction involves palladium‐catalyzed reduction, debenzylation and/or transimination and further reduction.     

An efficient microwave‐assisted synthesis of 3,5‐unsubstituted 4‐substituted‐6‐aryl‐3,4‐dihydropyridin‐2(1H)‐ones derivatives

Small libraries of 3,5‐unsubstituted 4‐substituted‐6‐aryl‐3,4‐dihydropyridin‐2(1H)‐ones derivatives were synthesized from the condensation‐products of aldehydes with Meldrum's acid, aromatic ketones and ammonium acetate using acetic acid as energy transferring‐agent under microwave irradiation without catalyst. This method has the advantages of excellent yields (65‐90%), short reaction time (5‐10 min) and being environmentally friendly. It aimed to provide new series of potential biologically active compounds for biomedical screening.     

(±)‐2‐alkyl‐1,2,3,4‐tetrahydroquinoline‐3‐carboxylic esters by a catalyst and pressure dependent tandem reduction‐reductive amination reaction

A series of 2‐(2‐nitrobenzyl)‐substituted β‐keto ester derivatives has been subjected to reductive cyclization under catalytic hydrogenation conditions. The reactions were found to be highly dependent on the catalyst and hydrogen pressure used. Hydrogenation over 5% palladium‐on‐carbon at 4 atmospheres pressure produced complex mixtures of products that included predominantly 1,2,3,4‐tetrahydroquinoline and quinoline products; at 1 atmosphere pressure, the same reactions gave mixtures containing predominantly tetrahydroquinoline and 1,4‐dihydroquinoline derivatives. Hydrogenation using 5% platinum‐on‐carbon was much cleaner and afforded the desired cis‐ and trans‐(±)‐2‐alkyl‐1,2,3,4‐tetrahydroquinoline‐3‐carboxylic esters, with the cis product predominating by ≥ 13:1.     

Synthesis and reactivity of 1‐amino‐4‐methyl‐3,4‐dihydro‐5H‐pyrazolo[3′,4′:4,5]pyrimido[1,6‐a]benzoimidazolo‐5‐one

Pyrimido[2“,1”:5′,6′]pyrazolo[3′,4′:4,5]‐pyrimido[1,6‐a]benzoimidazoloe‐2,8(1H,7H)‐diones, and [1,2,4]‐triazino‐[3“,4”:5′,6′]pyrazolo[3′,4′:4,5]pyrimido[1,6‐a]benzimidazol‐8(7H)‐ones were synthesized in a good yields via 1‐amino‐4‐methyl‐3,4‐dihydro‐5H‐pyrazolo[3′,4′:4,5]pyrimido[1,6‐a]benzoimidazolo‐5‐one and the appropriate active methylene compounds. Structures of the newly synthesized compounds were elucidated on the basis of elemental analyses, spectral data, and alternative synthesis methods whenever possible.     

Synthesis and biological properties of 1,8‐naphthalimidebutylamines. Serotonin 5‐HT1A and 5‐HT7 binding data and pass‐assisted search

Syntheses of the N‐substituted butyl derivatives of 1,8‐naphthalimide ( 1‐8 ), containing various arylpiperazines, tetrahydroisoquinoline and methylhomopiperazine moieties attached at 4‐position of the butyl chain have been described. Biological activities were evaluated in vitro for their ability to bind to serotonin 5‐HT_1A and 5‐HT₇ receptors. Due to the structural similarity of derivatives 1‐8 to psychotropic agents, the pharmacological properties of target compounds were predicted using PASS program.     

Synthesis of 5‐Hydroxy‐2‐(naphth‐2‐yl)chromone derivatives

The Diels‐Alder reaction of 5‐hydroxy‐2‐styrylchromones with ortho‐benzoquinodimethane, generated “in situ” by thermal extrusion of sulfur dioxide from 1,3‐dihydrobenzo[c]thiophene 2,2‐dioxide, leads to 2‐(3‐aryl‐1,2,3,4‐tetrahydronaphth‐2‐yl)‐5‐hydroxychromones. These cycloadducts were dehydrogenated with DDQ, using classical thermal reflux conditions and microwave irradiation, affording the corresponding 2‐(3‐arylnaphth‐2‐yl)‐5‐hydroxychromones in high yields (48‐96%).     

An Efficient synthesis of pyrimido[4,5‐b]quinoline and indeno[2′,1′:5,6]pyrido[2,3‐d]pyrimidine derivatives via multicomponent reactions in ionic liquid

A series of pyrimido[4,5‐b]quinoline and indeno[2′,1′:5,6]pyrido[2,3‐d]pyrimidine derivatives were synthesized via the three‐component reaction of an aldehyde, 6‐aminopyrimidine‐2,4‐dione and 5,5‐dimethyl‐1,3‐cyclohexanedione or 1,3‐indanedione in ionic liquid 1‐n‐butyl‐3‐methylimidazolium bromide ([bmim]Br). This protocol has the advantages of easier work‐up, milder reaction conditions, high yields and an environmentally benign procedure compared with other methods.