Three‐component,one‐pot synthesis of pyrimido[4,5‐b]‐quinoline and pyrido[2,3‐d]pyrimidine derivatives

Reaction of 6‐amino‐2‐methylthiouracil and 6‐amino‐1,3‐dimethyluracil with equimoler amounts of cyclic ketones or cyclic 1,3‐diketones and the appropriate aromatic aldehydes yielded regioselectivity a series of polycyclic pyrimido[4,5‐b]quinoline and pyrido[2,3‐d]pyrimidine derivatives in good yields.     

A convenient synthesis of pyrazolo[3,4‐d]pyrimidine‐4,6‐dione and pyrazolo[4,3‐d]pyrimidine‐5,7‐dione derivatives

Pyrazolo‐[3,4‐d]pyrimidine‐4,6‐diones 5 and pyrazolo[4,3‐d]pyrimidine‐5,7‐diones 7 were synthesized by Curtius rearrangement of pyrazolic mono‐esters 2 and 3 followed by hetero‐cyclization via the ureas derivatives 4 and 6 under alkaline conditions.     

Studies on uracils: A facile one‐pot synthesis of pyrazolo[3,4‐d]pyrimidines

The reaction of 6‐hydrazino uracils 1 and nitrones 2 result in an efficient one‐pot synthesis of pyrazolo[3,4‐d]pyrimidines 3 in excellent yields. The isolation of the by‐product aniline from the reaction mixture supported the plausible mechanism for the formation of pyrazolo[3,4‐d]pyrimidines.     

A three‐component,one‐pot synthesis of oxazinoquinolin‐3‐one derivatives

Oxazino[5,6‐f]quinolin‐3‐one derivatives have been synthesized in a one‐pot, and efficient process by condensation of 6‐quinolinol, aromatic aldehydes and urea under microwave‐assisted and thermal solvent‐free conditions.     

A convenient one‐pot synthesis and antimicrobial activity of pyrimido[1,2‐b][1,2,4,5]tetrazines

The synthesis of the hitherto unreported 3‐amino‐2,3‐dihydro‐6‐phenyl‐2‐thioxo‐4(1H)‐pyrimidine 2 and 3‐amino‐2‐methylthio‐6‐phenyl‐4(3H)‐pyrimidinone 3 is described. Reactions of hydrazonoyl halides 1 with either 2 or 3 afforded 6H‐pyrimido[1,2‐b][1,2,4,5]tetrazin‐6‐ones 6. The latter products were screened for their antifungal and antibacterial properties. The mechanism of the studied reactions is discussed.     

An efficient one‐pot synthesis of n‐carboxymethylacridine‐1,8‐dione derivatives under microwave irradiation

A series of N‐carboxymethylacridine‐1,8‐dione derivatives were synthesized by one‐pot reaction of aldehyde, dimedone and glycine in glycol under microwave irradiation without catalyst with excellent yields (78‐92%) and short reaction time (4‐8min). And the reaction was not only suitable for aromatic monoaldehyde, but also aromatic dialdehyde.     

A facile synthesis of novel thiazolo[4,5‐d]pyrimidin‐7‐ones

Sixteen 5‐alkylamino‐3,6‐diaryl‐2‐thioxo‐2,3,6,7‐tetrahydrothiazolo[4,5‐d]pyrimidin‐7‐ones 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j , 4k , 4l , 4m , 4n , 4o , 4p were designed and easily synthesized via a tandem aza‐Wittig reaction. The iminophosphorane 2 , obtained from reaction of 1 with triphenylphosphine, hexachloroethane and Et₃N, reacted with aromatic isocyanate to give carbodiimide 3 . carbodiimide 3 reacted with alkylamines to provide the title compounds in 45–61% isolated yields in presence of catalytic amount of ethoxide. The structures of compounds 4 were confirmed by ¹H NMR, IR, MS, and elemental analysis. J. Heterocyclic Chem., 2011.     

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).     

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.     

Molecular iodine‐catalyzed one‐pot synthesis of tetrahydrobenzo[a]xanthene‐11‐one and diazabenzo[a]anthracene‐9,11‐dione derivatives under microwave irradiation

An efficient one‐pot condensation of β‐naphthol, aldehydes, and cyclic 1,3‐dicarbonyl compounds has been achieved with molecular iodine as a catalyst under microwave irradiation, thus a variety of tetrahydrobenzo[a]xanthene‐11‐one and diazabenzo[a]anthracene‐9,11‐dione derivatives were prepared in good yields. J. Heterocyclic Chem., (2011).     

A facile one‐pot synthesis of novel substituted 1,2,3,4‐tetrahydropyrimidines

A facile one‐pot synthesis of 5‐benzoyl‐6‐methylthio‐1,2,3,4‐tetrahydropyrimidines in good yields is reported.     

A facile one‐pot synthesis of 2‐amino‐4‐arylbenzo[h]quinoline‐3‐carbonitrile derivatives without catalyst

A series of 2‐amino‐4‐arylbenzo[h]quinoline‐3‐carbonitrile derivatives were synthesized by one‐pot condensation of aromatic aldehyde, a‐naphthylamine and malononitrile in ethanol without catalyst. This multicomponent reaction has the notable advantages of short route, high yield and convenient operation.     

Microwave‐assisted efficient synthesis of benzo[4,5]imidazo[1,2‐a]‐pyrimidine derivatives in water under catalyst‐free conditions

Benzo[4,5]imidazo[1,2‐a]pyrimidine derivatives were synthesized via the three‐component reaction of aldehyde, β‐dicarbonyl compound and 2‐aminobenzimidazole in water under microwave irradiation and without catalyst conditions. The new protocol has the advantages of higher yield, lower cost, reduced environment impact, wider scope and convenient procedure.