An improved synthesis of pyrazolo[3,4‐b][1,5]benzoxazepine, ‐benzothiazepine and ‐benzodiazepine derivatives via a convenient one‐pot synthesis

An improved and simple method for the preparation of pyrazolo[3,4‐b][1,5]benzoxazepine, ‐benzothiazepine and ‐benzodiazepine derivatives was established by the reaction of 5‐chloro‐1‐phenylpyrazole‐4‐carbaldehydes, ethyl 3‐(5‐chloro‐1,3‐diphenylpyrazol‐4‐yl)‐2‐cyanoacrylate and 1,4‐diacetyl‐3‐methyl‐2‐pyrazolin‐5‐one with o‐aminophenol derivatives and o‐phenylendiamine.     

An efficient one‐pot synthesis of diarylpyrazolo[1,5‐a]pyrimidine from isoflavones

Direct synthetic methods of 6,7‐diphenylpyrazolo[1,5‐a]pyrimidine derivatives have been developed. Cyclocondensation of isoflavones with 3‐aminopyrazole in the presence of sodium methoxide as alkali promoter gave 6,7‐diphenylpyrazolo[1,5‐a]pyrimidines in moderate to good yields. J. Heterocyclic Chem., (2011).     

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 simple one‐pot synthesis of 1,2,3,4‐tetrahydro‐2‐thioxopyrimidine derivatives

5‐Benzoyl‐4‐(substituted phenyl)‐6‐phenyl‐1,2,3,4‐tetrahydro‐2‐thioxopyrimidines ( 4a‐d ) were synthesized using the Biginelli three component cyclocondensation reaction of an appropriate β‐diketone, arylaldehyde, and thiourea in acetic acid under reflux condition in approximately 52‐65% yields. The acetylation of compounds 4a‐d gave 3‐acetyl thioxopyrimidine derivatives 5a‐d . Also, pyrimidothiazine compounds 6a‐d were prepared by a simple one‐pot condensation reaction of starting pyrimidine derivatives 4a‐d and 3‐bromopropionic acid. The structures of compounds were characterized on the basis of elemental analyses, IR, ¹H and ¹³C‐NMR spectra.     

New Synthesis of Pyrazolo[3,4‐b][1,4,5]benzothiadiazepine, ‐[1,4,5]benzoxadiazepine, ‐[1,4,5]benzotriazepine and Pyrazolo[3,4‐b]quinoxaline Derivatives

New pyrazolo[3,4‐b][1,4,5]benzothiadiazepine and its analogues 3 have been obtained by reaction of 4‐nitrosopyrazoles 1 with 2‐aminothiophenol 2a and its analogues 2b,c . Under fused conditions, dipyrazolyl derivatives 7a was obtained with a trace amount of quinoxaline 5a . On the other hand, 5b and 7b were obtained in equal amounts. A proposed pathway is presented.     

An efficient one‐pot synthesis of pyrazolo[3,4‐b]pyridinone derivatives catalyzed by L‐proline

A series of 3‐methyl‐1,4‐disubstituted‐4,5‐dihydro‐1H‐pyrazolo[3,4‐b]pyridine‐6(7H)‐ones was synthesized via the three‐component reaction of aldehyde, 3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐amine, and Meldrum's acid catalyzed by L ‐proline. This protocol has the advantages of easier work‐up, milder reaction conditions, and high yields. J. Heterocyclic Chem., (2011).     

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.     

Efficient one‐pot synthesis of s‐triazolo[3,4‐b]‐[1,3,5]thiadiazines containing a chiral side chain by double mannich type reaction

An efficient and convenience method has been developed via a one‐pot double Mannich type reaction for the synthesis of the important chiral s‐triazole derivatives: (S)‐3‐α‐phenylethyl‐2,4‐dihydro‐5‐aryl‐oxymethyl‐1,2,4‐triazolo [3,4‐b] ‐1,3,5 ‐thiadiazines.     

Novel synthesis of 3‐phenylazo‐1,5‐benzothiazepines, ‐1,5‐benzoxazepines and ‐1,5‐benzodiazepines via a one‐pot reaction

Novel polysubstituted ‐1,5‐benzothiazepine, ‐1,5‐benzoxazepine, and ‐1,5‐benzodiazepine were prepared in good yields by the reaction of hydrazono derivatives with o‐thioaminophenol, o‐aminophenol and o‐phenylenediamine via a one‐pot reaction.     

New one‐ pot synthesis of pyrazolo[3,4‐c]pyridazine and isoxazolo‐[5,4‐b]pyridine derivatives from potassium cyanoacetahydroxamate

The reaction of potassium cyanoacetohydroxamate 1 with ethyl 2‐aryl‐hydrazono‐3‐oxobutyrates 2 gave the unexpected pyrazolo[3,4‐c]pyridazines 7 and isoxazolo[5,4‐b]pyridines 10 via a one‐pot reaction. A mechanistic proof is suggested to account for the products.     

Solvent‐free one‐pot synthesis of pyrane derivatives

A straightforward and an efficient method for the synthesis of 2H‐pyrans via the one‐pot, reaction of alkyl bromides, carbon disulfide, secondary amines, activated acetylenes and isocyanides under solvent‐free conditions without using any catalyst at room temperature is reported. The method offers several advantages including high yields of products and an easy work‐up procedure. J. Heterocyclic Chem., (2011).     

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).     

An efficient one‐pot synthesis of pyrimido[2,1‐b][1,3]oxazine derivatives via the reaction of isocyanides with dialkyl acetylenedicarboxylates in the presence of 5‐substituted uracils

The reactive 1:1 intermediate produced in the reaction between alkyl isocyanides and dialkyl acetylenedicarboxylates was trapped by uracil and its 5‐substituted derivatives to yield highly functionalized pyrimido[2,1‐b][1,3]oxazine derivatives in fairly good yields. J. Heterocyclic Chem.,(2011).     

A library of pyranocoumarin derivatives via a one‐pot three‐component hetero diels‐alder reaction

A hetero Diels‐Alder reaction with inverse electron demand between 4‐hydroxycoumarin, aromatic aldehydes and electron‐rich alkenes yielded a multitude of 2,4‐disubstituted 3,4‐dihydropyranocoumarins. This route opened an easy access to coumarin anticoagulants and provided a library of pyranocoumarin derivatives.     

Novel and efficient one‐pot synthesis of azuleno[1,2‐b]‐benzothiophenic enones from the corresponding 2‐cycloheptatrientyl‐3‐(2‐furyl)benzothiophenes

2‐Cycloheptatrienyl‐3‐(2‐furyl)benzothiophenes, which are prepared by Stille coupling reaction of 2‐cyclo‐heptatrienyl‐3‐bromobenzothiophene with the 5‐substituted 2‐trimethylstannylfurans, react with triphenylmethyl tetrafluoroborate to give the corresponding azuleno[1,2‐b]benzothiophenic enones in excellent yields.     

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.     

One‐pot synthesis of tetrahydroindeno[1,2‐b]pyrrolo‐3‐carboxylates derivatives

Tetrahydroindeno [1,2‐b]pyrrole‐3‐carboxylate were synthesized in a one‐pot procedure by the reaction of 1,3‐dicarbonyl and activated carbonyl compounds such as benzyl or ninhydrin in ethanol/water in the presence of ammonium acetate. J. Heterocyclic Chem., (2011).     

Carbazolo[2,1‐a]carbazole derivatives via fischer indole synthesis

A series of new carbazolo[2,1‐a]carbazoles was synthesized from 4‐oxo‐1,2,3,4‐tetrahydrobenzo[a]‐carbazole derivatives.     

An efficient one‐pot synthesis of 2‐benzylpyrroles and 3‐benzylindoles

One‐pot regioselective benzylation of pyrroles and indoles using zirconium tetrachloride is discussed. This has been achieved by in‐situ generation of di(1H‐pyrrol‐1‐yl)zirconium(IV) chloride and di(1H‐indol‐1‐yl)zirconium(IV) chloride. It was observed that benzylation reactions of these complexes using n‐BuLi occurred at C‐2 position for pyrrole and C‐3 for indole. Copyright © 2011 John Wiley & Sons, Ltd.