Synthesis of 5‐substituted 2‐(2,4‐dihydroxyphenyl)‐1,3,4‐thiadiazoles

One‐stage synthesis of 5‐substituted (alkyl, aryl, heteroaryl, arylalkyl, heteroalkyl, alkoxy‐, aryloxy)‐2‐(2,4‐dihydroxyphenyl)‐1,3,4‐thiadiazoles is described. The compounds were prepared by the reaction of sulfinyl‐bis(2,4‐dihydroxythiobenzoyl) (STB) with hydrazides or carbazates. The structure of new compounds was assigned by ir, nmr and ms data.     

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.     

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.     

The synthesis of chromophore ended glycoles,part IV. Bis‐coumarin derivatives ended polyglycols

The coumarin derivatives of bis‐resorcin ended polyglycols were prepared in two ways: Bis‐4‐alkyl‐7‐oxycoumarin ended mono and diethyleneglycols were prepared starting from bis(3‐hydroxyphenyl)glycols by coumarin condensation using relevant β‐ketoesters. Accordingly, 4‐methyl, 4‐trifluoromethyl, 4‐n‐propyl and 4‐phenyl derivatives of 7‐hydroxycoumarins were prepared in good yields. They were then converted to bis‐coumarin ended three and tetraethylenglycol derivatives by reacting with three and tetraethyleneglycols dichlorides in Na₂CO₃/DMF, respectively. The products were identified using IR, ¹H nmr and low resolution mass spectrometry. The Li⁺, Na⁺ and Rb⁺ metal/Ligand selectivities of cation binding behaviour of products in acetonitrile were studied with steady state fluorescence spectroscopy.     

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.     

Synthesis of novel substituted flavonoids

Eighteen substituted chalcones, flavones and 3‐flavonols were synthesized and characterized using ¹H‐NMR, IR and elemental analysis. The substitution pattern includes two halogen atoms, nitro and methyl groups in ring A as well as two or three methoxy groups in ring B.     

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.     

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.     

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 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.     

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 .     

Cyclization of 2‐benzoylamino‐N‐methyl‐thiobenzamides to 3‐methyl‐2‐phenylquinazolin‐4‐thiones

Acylation of 2‐amino‐N‐methyl‐thiobenzamide with substituted benzoyl chlorides has been used to synthesize the corresponding 2‐benzoylamino‐N‐methylthiobenzamides. Subsequent sodium methoxide‐catalyzed ring closure gives the corresponding 3‐methyl‐2‐phenylquinazoline‐4‐thiones. These compounds were characterized by means of their ¹H‐ and ¹²C‐NMR spectra. The kinetics of the cyclization reaction has been followed with UV‐VIS spectroscopy at 100 °C in methanolic solutions of sodium methoxide.     

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.     

Synthesis of new TTF‐anthracene dyads as potential fluorescence probe for 1O2

Three new fluorescence probes for ¹O₂ with different electron‐rich tetrathiafulvalene and anthracene units have been synthesized and characterized. Among them, compound 3c, 2,3‐bis[2‐(9‐anthryloxy) ethylthio]‐6,7‐(propylenedithio)‐1,4,5,8‐tetrathiafulvalene, is very sensitive and may act as the fluorescence probe for ¹O₂.     

Alpha vinylation of haloquinoline‐5,8‐diones with methyl acrylate and methyl vinyl ketone under baylis‐hillman reaction conditions

A synthesis of mono‐ and di‐vinylquinolinediones based on substitution of the halogens in 6,7‐dihaloquinoline‐5,8‐diones by DABCO‐assisted enolate ion is described. Divinylquinolines undergo 6π‐electrocyclization by thermally to give the benzo[g]quinoline derivatives.     

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.     

The dipolar route to naphtho[2,1‐c]isoxazoles from the baylis‐hillman adducts of 2‐alkynylbenzaldehydes

A new synthesis of 4‐carbomethoxynaphtho[2,1‐c]isoxazoles 4a‐d from methyl 3‐(alkynylphenyl)‐2‐nitromethyl‐2‐propenoates 2a‐d by the intramolecular nitrile oxide cycloaddition is described. The latter are readily obtained from 2‐alkynylbenzaldehydes through the Baylis‐Hillman adduct acetates 1a‐d followed by nucleophilic substitution of nitrite anion.     

New synthesis,x‐ray structural determination,conformational analysis and anomeric effect study of 3,7‐di (3‐nitrophenyl)‐1,5‐dioxa‐3,7‐diazacyclooctane

3,7‐Di(3‐nitrophenyl)‐1,5‐dioxa‐3,7‐diazacyclooctane was prepared from 3‐nitroaniline and formaldehyde in acetonitrile. Conformational behavior of ring inversion of the molecule was studied so it prefers a crown conformation. The evaluated ΔG^* was approximately 58.0 ± 1.0 kJ/mole. The X‐ray structure determination of the compound shows a crown conformation, in line with two‐anomeric effect in N‐C‐O moiety.     

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.