Cyclocondensation reactions of heterocyclic carbonyl compounds XII. The double course of cyclization of 3‐(2‐aminobenzyl)‐1,2‐dihydro‐quinoxaline‐2‐one

The cyclocondensation reaction of compound 1 in boiling hydrochloric acid had an unexpected course. Instead of supposed 5,11‐dihydro‐quinoxalino[2,3‐b]quinoline 6a , 2‐(indol‐2‐yl)‐benzimidazole 4 was isolated as the major product.     

Synthesis and characterization of 4‐aryl‐5‐(1‐aryl‐2‐methyl‐2‐nitropropyl)‐1,2,3‐selenadiazoles

The synthesis of a new set of selenadiazoles, 4‐aryl‐5‐(1‐aryl‐2‐methyl‐2‐nitropropyl)‐1,2,3‐selenadiazoles ( 4 ) derived from 2‐[4‐methyl‐4‐nitro‐1,3‐diarylpentylidene]‐1‐hydrazinecarboxamide ( 3 ) has been reported. THF has been found to be the solvent of choice for this reaction. Structural features of 3 and 4 have been analyzed by NMR and X‐ray techniques.     

Synthesis of 1‐(substituted phenylcarbonyl/sulfonylamino)‐1,2,3,6‐tetrahydropyridine‐5‐carboxylic acid diethylamides as potential anti‐inflammatory agents

Fifteen novel 1‐(substituted phenylcarbonyl/sulfonylamino)‐1,2,3,6‐tetrahydro‐ pyridine‐5‐carboxylic acid diethylamide ( 7, 15 ) were synthesized in fair to good yields via sodium borohydride reduction of the corresponding 1‐(substituted phenylcarbonyl/ sulfonylimino)‐3‐diethylcarbamoyl pyridinium ylides ( 6, 14 ) in absolute ethanol.     

Convenient synthesis of N‐substituted 1‐alkyl and 1‐aryl‐3‐aminoisoquinolines

Cyclocondensation of 2‐acylphenylacetonitriles 1 with amines affords 1‐substituted 3‐aminoisoquinolines 2 in good yields.     

Microwave induced synthesis of the thiazolidine‐2,4‐dione motif and the efficient solvent free‐solid phase parallel syntheses of 5‐benzylidene‐thiazolidine‐2,4‐dione and 5‐benzylidene‐2‐thioxo‐thiazolidine‐4‐one compounds

Novel microwave induced method for the synthesis of thiazolidine‐2,4‐dione motif under solvent phase conditions is developed. Further we report an efficient, microwave assisted method for the parallel syntheses of biologically important 5‐benzylidene‐thiazolidine‐2,4‐dione and 5‐benzylidene‐2‐thioxothiazolidine‐4‐one compounds under solid‐phase and solvent‐free conditions. A comparative study between the developed microwave methods and the conventional methods is described. We have also illustrated the possible mechanism behind to address the reason why piperidine, acetic acid and silica gel enhanced the Knoevenagel condensation reaction.     

Synthesis of 2‐phenylquinolin‐4‐amines substituted with diverse amino and aminoalkyl groups

Facile synthetic approaches to 2‐phenylquinolin‐4‐amines containing an aminoalkyl group at N⁴ of the quinolin‐4‐amine and amino or aminoalkyl groups at the phenyl moiety are presented.     

New fragmentation of 2‐isoxazoline‐5‐carboxylic acid chlorides

A novel base promoted degradation of 3‐aryl‐2‐isoxazoline‐5‐carboxylic acid chlorides to aryl nitriles has been discovered.     

Facile preparation of 7,11‐di(4‐nitrobenzenesulfonyl)‐diaza‐1,4‐dioxa‐7,11‐spiro[4,7]dodecan‐9‐one

Compound 1 as a key intermediate for the synthesis of 3,3,7,7‐tetrakis‐(difluoroamino)octahydro‐1,5‐dinitro‐1,5‐diazocine (HNFX) and 3,3‐bis(difluoroamino)octahydro‐1,5,7,7‐tetranitro‐1,5‐diazocine (TNFX) is described. Cycloalkylation of 3 with 1,3‐dibromopropan‐2‐ol ( 4 ) afforded 1,5‐protected‐1,5‐diazocine 2 , followed by chromic acid oxidation to ketone 1 in good yield.     

Synthetic study for two 2H‐chromenic acids, 8‐chlorocannabiorcichromenic acid and mycochromenic acid

Two 2H‐chromenes having a fully substituted benzene ring, 8‐chlorocannabiorcichromene ( 1 ) and mycochromenic acid ( 2 ), were synthesized by a condensation of salicylaldehydes with isopropylidenemalonate or the thermal cyclization of corresponding propargyl ethers.     

Synthesis of 9‐[1‐benzyl‐5‐(alkylsulfonyl)‐1H‐2‐imidazolyl]perhydro‐1,8‐acridinediones

Tricyclic dihydropyridines like ZM244085 are potential K_ATP channel openers. In this study 3‐cyanophenyl ring of ZM244085 was replaced with imidazolyl ring. So, 9‐[1‐benzyl‐5‐(alkylsulfonyl)‐1H‐2‐imidazolyl]perhydro‐1,8‐acridinediones ( 5d‐f ) were synthesized from 2‐alkylsulfonyl‐1‐benzyl‐5‐formylimidazole ( 4d‐f ) and cyclohexane‐1,3‐dione according to classical Hantzch synthesis as potential potassium channel modulators.     

Reactions of cephalosporin sulfones 3. Synthesis of 2‐phenylhydrazonocephem‐sulfones. A new potential entry to 2‐aminocephems

Reaction of cephem sulfones 1a‐e with aryldiazonium salts gives the 2‐azo compounds which immediately rearrange into the corresponding 2‐hydrazono derivatives 2a‐e .     

Synthesis and antimicrobial activity of new benzofuranyl‐1,3‐benzoxazines and 1,3‐benzoxazin‐2‐ones

New benzofuranyl‐1,3‐benzoxazines and 1,3‐benzoxazin‐2‐ones are synthesized in which benzofuran is coupled with 1,3‐benzoxazines and 1,3‐benzoxazin‐2‐ones through ‐CONH‐ and ‐COCH₂‐ bridges, respectively. The antimicrobial activity of these compounds is reported.     

Synthesis of some new spiro naphtho[2,3‐d][1,3]dithiole‐4,9‐dione derivatives

2(1‐Acetyl‐2‐oxopropylidene)naphtho[2,3‐d][1,3]dithiole‐4,9‐dione 1 reacts with a variety of bidentates reagents to give some new functionally substituted spiro naphthodithiole‐4,9‐dione derivatives.     

A practical synthesis of 5‐(4′‐methylbiphenyl‐2‐yl)‐1H‐tetrazole

Practical synthesis of 5‐(4′‐methylbiphenyl‐2‐yl)‐1H‐tetrazole, key intermediate in several angiotensin II receptor antagonists from 2‐fluorobenzonitrile in excellent yields and very high purity is described.     

Synthesis of some new 4‐substituted‐3, 5‐bis(2‐pyridyl)‐1h‐pyrazole

Several 4‐substituted‐3, 5‐bis(2‐pyridyl)‐1H‐pyrazoles, where the substituent is chloro, bromo, iodo, nitro, diazo, were synthesized under mild reaction conditions in high yields. The structures of the products were characterized by ¹H NMR, ¹³C NMR, ESI‐MS, IR and elemental analyses.     

Δ2‐Isoxazolines from β,γ‐unsaturated oximes

3,5‐Disubstituted Δ²‐isoxazolines can be prepared using the palladium‐mediated nucleometalation / methoxycarbonylation of β,γ‐unsaturated oximes. This novel route to this class of compounds is tolerant of a wide variety of functionality in the starting material, and provides a rapid route to highly functionalized isoxazolines.     

Reactions of 2‐amino‐4h‐1‐benzopyran‐4‐one with 4‐oxo‐4h‐1‐benzopyran‐3‐carbaldehydes

The title aldehyde 1 reacts smoothly with the enamine moiety of 2 ‐aminochromone 2 to produce hitherto unreported 3‐(2‐hydroxybenzoyl)‐5H‐1‐benzopyrano[2,3‐b]pyridin‐5‐one (azaxanthone) 5 . This reaction has been extended for the synthesis of bisazaxanthone 9.     

Cycloaddition reaction of schiff bases with ketenes generated by pyrolysis of 2‐aryl‐substituted 1,5,7‐trioxaspiro[2.5]octane‐4,8‐diones

The α‐oxo ketenes 6 which are generated by the pyrolysis of the 2‐aryl‐substituted 1,5,7‐trioxaspiro[2.5]octane‐4,8‐diones 1 , were reacted with Schiff bases 2 to give spiro compounds constructed between the β‐lactam and 1,3‐dioxolan‐4‐one; i.e., the 2,3,6‐triaryl‐2‐aza‐5,7‐dioxaspiro[3.4]octane‐1,8‐diones 3 and 4 . Hydrogenation of the mixture of 3a and 4a in the presence of catalytic amount of Pd‐C produced the trans‐2‐benzyloxy‐1,4‐diphenyl‐β‐lactam‐3‐carboxylic acid 9 .     

Synthesis of N‐benzoylamino‐1,2,3,6‐tetrahydropyridine derivatives as potential anti‐inflammatory agents

N‐Benzoylamino‐1,2,3,6‐tetrahydropyridines 9a‐q were synthesized from 4‐substituted pyridines in four steps. Amination of pyridines was carried out to prepare intermediate N‐aminopyridinium mesylates using mesytelenesulfonyl hydroxmate (MSH) as aminating agent. N‐aminopyridinium mestylates reacted with appropriately substituted acyl chlorides to form N‐ylides as stable crystalline solids. Partial reduction of N‐ylides with mild reducing agent afforded N‐benzoylamino‐1,2,3,6‐tetrahydropyridines in fair to good yields.