Synthesis of an 4‐oxo‐1,4‐dihydropyridinomethylidene substituted 2‐indolinone

The (Z)‐3‐substituted 2‐indolinone 6 was prepared using the aldehydes 4 and 8 unknown up to now and 2‐indolinone.     

Synthesis of new spiro‐[isothiochromene‐3,5′‐isoxazolidin]‐4(1H)‐ones

A series of seven new 2′,3′,4′‐substituted spiro[isothiochromene‐3,5′‐isoxazolidin]‐4(1H)‐ones ( 7‐13 ) has been prepared in the reaction of benzylidene(phenyl)azane oxide ( 5 ) or benzylidene(methyl)azane oxide ( 6 ) with (3Z)‐3‐(4‐substituted‐benzylidene)‐1H‐isothio‐ chromen‐4(3H)‐one ( 1‐4 ). The reaction occurs by a 1,3‐dipolar cycloaddition mechanism that leads to the regiospecific formation of various spiroisoxazolidines ( 7‐13 ).     

Facile three‐component one‐pot synthesis of indeno‐[1,2‐b]quinolin‐9,11(6H,10H)‐dione derivatives

One‐pot three‐component cyclocondensation of aldehydes, 1,3‐indanedione and enaminones proceeds in the presence of acetic acid to afford Indeno[1,2‐b]quinolin‐9,11(6H,10H)‐dione derivatives, The method has the advantage of excellent yields(85‐94%) and simple workup procedure.     

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 4‐amino‐5,6,7,8‐tetrahydrothieno[2,3‐b]quinolin‐5‐ol derivatives

This paper describes the synthesis of 4‐amino‐5,6,7,8‐tetrahydrothieno[2,3‐b]quinolin‐5‐ol derivatives ( 3a‐h ) and 4‐amino‐5,6,7,8‐tetrahydrothieno[2,3‐b]quinoline ( 8a ) in good yield by three‐step procedures starting from 2‐aminothiophene‐3‐carbonitrile and 5‐substituted cyclohexane‐1,3‐dione.     

Synthesis of a novel class of 3‐(2′‐benzothiazolyl)‐2,3‐dihydroquinazolin‐4(1H)‐ones under solvent‐free and catalyst‐free conditions

A solvent‐ and catalyst‐free one‐pot three‐component condensation reaction approach was developed for the synthesis of a new class of 3‐(2′‐benzothiazolyl)‐2,3‐dihydroquinazolin‐4(1H)‐ones in relatively good yields.     

Regioselective synthesis of pentacyclic polyheterocycles: Sequential [3,3] sigmatropic rearrangement of 4‐(4′‐aryloxybut‐2′‐ynyloxy)‐1‐phenyl‐1,8‐naphthyridin‐2(1H)‐ones

A number of 4‐aryloxymethyl‐6‐phenyl‐2H‐pyrano[3,2‐c][1,8]naphthyridin‐5(6H)‐ones ( 4a‐f ) are regioselectively synthesized in 72‐78% yield by the Claisen rearrangement of 4‐(4′‐aryloxybut‐2′‐ynyloxy)‐1‐phenyl‐1,8‐naphthyridin‐2(1H)‐ones ( 3a‐f ) in refluxing chlorobenzene for 4‐6 h. These products are then subjected to a second Claisen rearrangement catalyzed by anhydrous AlCl₃ at room temperature for 2 h to give hitherto unreported pentacyclic heterocycles ( 5a‐f ) in 78‐85% yield.     

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.     

New isochromans. 1. Synthesis and antimicrobial activity of 4‐substituted (±)‐1h‐spiro[benzo[c]pyran‐3(4H), 1′‐cyclohexane]‐1‐ones

The reaction between homophthalic anhydride and cyclohexanone was examined both in the presence of DMAP or BF₃·Et₂O complex as a catalyst. The latter yielded (±)‐1‐oxo‐1H‐spiro[benzo[c]pyran‐3(4H), 1′‐cyclohexane]‐4‐carboxylic acid ( 3 ) in a higher yield (82 %). A series of new (±)‐4‐(N,N‐disubstituted‐1‐carbamoyl)‐1H‐spiro[benzo[c]pyran‐3(4H),1′‐cyclohexane]‐1‐ones ( 5a‐h ) were synthesized from the parent acid 3 by a two‐step reaction. Differentiating microbial screening was performed for most of the synthesized compounds against twelve microorganisms belonging to different taxonomic groups. The spiro acid 3 was active against all bacterial strains with MIC ≥ 20 μg/ml against B. subtillis and P. vulgaris. E. coli was the most sensitive strain to the antibacterial effect of the tested compounds.     

Synthesis and stereochemistry of 3‐acetyl‐5‐aminospiro[1,3,4‐thiadiazoline‐2,4′‐thioflavans]

Under acetylating conditions racemic thioflavanone thiosemicarbazones cyclize into racemic 3‐acetyl‐spiro[1,3,4‐thiadiazoline‐2,4′‐thioflavans] and a racemic 3‐acetylspiro[1,3,4‐oxadiazoline‐2,4′‐thioflavan] with trans O(1) or S(1) and Ph(2′_eq). Hindered rotation of the endocyclic N(3) acetyl group spirothia‐diazolines caused the formation of isomers separable by HPLC. X‐ray diffraction analyses, ¹H‐, ¹³C‐, and ¹⁵N NMR measurements as well as MOPAC QM calculations were performed to reveal the structures of these isomers.     

Retro‐ene reactions in heterocyclic synthesis. v. a novel synthetic method for 1,3,5‐triazine‐2,4(1H,3H)‐diones

N‐t‐Butylamidines 1 on heating with diphenyl carbonate ( 2 ) at 150‐180° gave the 1,3,5‐triazine‐2,4(1H,3H)‐dione derivatives 5 . Acylation of amidines 1 and cyclocondensation of the resulting carbamates 3 gave [1,3,5,7]tetrazocine‐2,6‐dione derivatives 4 , and subsequent retro‐ene reaction and ring contraction afforded triazine derivatives 5 .     

Diverse reactivity of α‐carbanions derived from alkylidenephosphoranes toward 2‐(1λ5‐diazynylidene)‐1H‐indene‐1,3‐(2H)dione. General approach to conjugated oxadiazines,pyridazines and spiro[3]pyrazoles

Different types of phosphonium carbanions were applied to 2‐diazonio‐1,3‐dioxo‐2,3‐dihydro‐1H‐inden‐2‐ide ( 1 ) in order to synthesize a number of condensed and fused N‐heterocycles. When 1 was treated with cyanomethyltriphenylphosphonium chloride oxadiazine‐, and pyridazine derivatives were obtained whereas bis‐indanylidene derivatives resulted from the reaction of 1 with methyl_ and ethyltriphenylphosphonium bromides. On the other hand, a series of substituted and unsubstituted spiro[3′]pyrazoles were obtained from the di azo substrate when reacted with vinyl_and allyltriphenylphosphonium bromides.     

An efficient synthesis of new benzo[1′,2′:6,7]quinolino[2,3‐d]‐pyrimidine derivatives via three‐component microwave‐assisted reaction

A series of benzo[1′,2′:6,7]quinolino[2,3‐d]pyrimidine derivatives were synthesized via condensation of an aromatic aldehyde, 2‐hydroxy naphthalene‐1,4‐dione and 2,6‐diaminopyrimidin‐4‐one in mixed solvent of acetic acid and glycol (3:1,V:V) under microwave irradiation. This one‐pot protocol has the advantage of good yield (86‐91%), simple workup procedure and rapid reaction time (4‐8min).     

An efficient synthesis of new pyrido[4′,3′:4,5]thieno[2,3‐d]‐pyrimidin‐4(3H)‐one derivatives

The carbodiimides 5 , obtained from reactions of iminophosphorane 4 with aromatic isocyanates, reacted with amines, phenols or ROH to give 2‐substituted 5,6,7,8‐tetrahydropyrido[4′,3′:4,5]thieno[2,3‐d]‐pyrimidin‐4(3H)‐one 7 in the presence of catalytic amount of sodium alkoxide or solid potassium carbonate in satisfactory yields.     

An efficient and green synthesis of 3,3′‐benzylidenebis (4‐hydroxy‐6‐methylpyridin‐2(1H)‐one) derivatives through multi‐component reaction in ionic liquid

A series of new 3,3′‐benzylidenebis(4‐hydroxy‐6‐methylpyridin‐2(1H)‐one) derivatives were synthesized via a three‐component reaction of an aldehyde, an aniline or ammonium acetate and 6‐methyl‐4‐hydroxypyran‐2‐one in ionic liquid. These heterocyclic compounds produced could be conveniently separated from the reaction mixture without any volatile organic solvents, and the ionic liquid could be readily reused without efficiency loss after simple treatment.     

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 of novel 3,5,7‐triaryl‐5,6‐dihydro‐4h‐1,2,5‐triazepines

Several hitherto unknown 3,5,7‐triaryl‐5,6‐dihydro‐4H‐1,2,5‐triazepines have been synthesised by cyclocondensation of N,N‐bis(phenacyl)anilines with hydrazine hydrate in ethanol or ethyleneglycol under reflux condition. Increased yields were obtained in the presence of p‐toluenesulfonic acid compared to the uncatalysed reaction.     

Synthesis and antifungal activity of spiro[cyclopropane‐1,4′‐pyrazol‐3‐one] derivatives

A series of new spiro[cyclopropane‐1,4′‐pyrazol‐3‐one] derivatives 3a‐h were synthesized by the reaction of 4‐arylidene‐3H‐pyrazol‐3‐one 1 with secondary and tertiary carbanions derived from a methylene and methine group bearing both a leaving group and electron‐withdrawing group, e.g. methyl chloroacetate, ethyl chloroacetate, isopropyl chloroacetate, tert‐butyl chloroacetate, chloroacetonitrile, 2‐chloro‐N,N‐diethylacetamide, methyl 2‐chloropropionate and 2‐chloropropionitrile, in the presence of sodium hydride. All the synthesized compounds 3a‐h were active against Candida albicans with MIC ≤ 25 μg/mL in vitro.     

Chemoselective reaction of formalin with 2‐(5‐substituted‐2‐hydroxybenzylamino)phenols: Synthesis of 6‐substituted 3‐(2‐hydroxyphenyl)‐3,4‐dihydro‐2H‐benzo[e][1,3]oxazines

Reaction of 2‐(5‐substituted‐2‐hydroxybenzylamino)phenols ( 2 ) with formalin in ethanol under reflux has chemoselectively led to 2‐(6‐substituted‐2H—benzo[e][1,3]oxazin‐3(4H)‐yl)phenols ( 3 ) in good yield involving the ring closure of the hydroxyl group of the C‐aryl ring and not that of the N‐aryl ring.     

An improved synthesis of 1‐acetyl‐1H‐indol‐3‐yl acetates

An efficient two steps procedure for the synthesis of 1‐acetyl‐1H‐indol‐3‐yl acetates, starting from 2‐chlorobenzoic acids, was developed and in general, moderate to good yields were obtained