One‐pot synthesis of hexahydroquinolines Via a four‐component cyclocondensation under microwave irradiation in solvent free conditions: A green chemistry strategy

Four‐component cyclocondensation of aromatic aldehydes, malononitrile, dimedone and ammonium acetate proceeds under microwave irradiation in solvent free conditions to give highly functionalized hexahydroquinolines in excellent yields.     

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 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.     

Convenient synthesis of some 2‐substituted 4(3H)‐quinazolinone derivatives

A series of 2‐substituted‐4(3H)‐quinazolinones 13‐20 has been synthesized in good yields using the reaction of double lithiated 2‐methylquinazolinone‐4 with a variety of aromatic aldehydes. They have been easily transformed in high yields into the corresponding 2‐substituted conjugated derivatives 21‐28 bearing terminal aryl groups by F₃CCOOH mediated dehydration.     

1,8‐Diazafloren‐9‐one with alkyl and aryl isocyanides in the presence of acetylenic esters: A facile synthesis of γ‐spiroiminolactones

The 1:1 intermediate generated by the addition of alkyl and aryl isocyanides to dialkyl acetylenedicarboxylate is trapped by 1,8‐diazafloren‐9‐one to yield iminolactones in good yields.     

A general synthesis of 8‐hydroxy‐6‐substituted‐1,7‐naphthyridines

A general method for the synthesis of 8‐hydroxy‐6‐substituted‐1,7‐naphthyridines is described using acylation of the dianion derived from tert‐butylamide 1 , followed by cyclization of the resulting intermediate ketones 2 with ammonium acetate.     

Cyclocondensation of amidines with dimethyl acetylenedicarboxylate: A convenient entry into tetramic acids

Amidines undergo cyclocondensations with dimethyl acetylenedicarboxylate (DMAD) to give highly functionalized 5‐dialkylamino‐4‐pyrrolin‐3‐ones. The products are crystalline, highly colored compounds that are uniquely functionalized and represent advanced intermediates in the construction of several other heterocyles, in particular the biologically active tetramic acids. The synthetic transformations of these compounds to tetramic acids are also described.     

One‐pot synthesis of 2‐aminobenzothiazoles using a new reagent of [bmim]br3 in [bmim]BF4

The one‐pot direct synthesis of 2‐aminobenzothiazoles from phenyl isothiocyanate and amines using a new reagent of 1‐butyl‐3‐methylimidazolium tribromide ([Bmim]Br₃) in ionic liquid 1‐butyl‐3‐methylimidazolium tetraflouoroborate ([Bmim]BF₄) is described.     

Stereocontrolled synthesis of tricyclic fused oxazolidinone as antibacterial agent

Tricyclic fused oxazolidinone 3a and 3b have been synthesized as antibacterial agents in 12 and 11 steps respectively. The key intermediates 10a and 10b have been developed via opening of epoxide 9a and 9b and cyclization by the resulting oxygen anion attack.     

Syntheses,electrochemical studies and crystal structures of new unsymmetrical tetrathiafulvalene carboxylate derivatives

A series of new unsymmetrical tetrathiafulvalene carboxylate derivatives ( 7‐11 ) were synthesized and characterized by NMR, MS, electrochemical studies and X‐ray crystal structural determination. Compound 8 showed obvious changes in redox peak potentials as the concentration of p‐toluenesulfonic acid changes.     

Structure of the tetramer of α-methylstyrene

The structure of the tetrameric dianion formed by α-methylstyrene in tetrahydrofuran by reaction with sodium has been examined. Mass spectral, NMR, infrared, and kinetic data all indicate that the structure is rather than the structure which had previously been assumed for this species.     

Mn(III) acetate mediated diasteroselective [3+2] oxidative addition of 1,3‐dicarbonyl compounds with chalcones

A diastereoselective synthesis of 4,5‐dihydrofurans by oxidative addition of 1,3‐dicarbonyl compounds with chalcones mediated by Mn(OAc)₃ in moderate to good yields is reported.     

Practical Microwave Synthesis for Organic Chemists.Strategies,Instruments, and Protocols. Herausgegeben von C. Oliver Kappe,Doris Dallinger und Shaun Murphree.

Wiley‐VCH, Weinheim 2008. 300 S., geb., 59.00 €.—ISBN 978‐3527320974

     

Synthesis of 7a‐aryl‐5‐t‐butyl‐3‐methyleneoctahydrobenzofuran possessing partial skelotons of some santonin analogue and furanolignans by intramolecular radical cyclisation reaction

Bicyclic octahydrobenzofuran derivatives ( 1c‐6c ) possessing the partial skeletons of santonin ( 7 ), 11,13‐dehydroisohyposantonin ( 8 ), dihydrosesamin ( 9 ) and lariciresinol ( 10 ) have been synthesised by intramolecular radical cyclisation in good yield via the precursors viz., the trans diaxial bromopropynyl ethers ( 1b‐6b ) obtained in highly regio/stereoselective manner.     

Spectrophotometric Studies of Uranyl(VI) Chelate of β-Isopropyltropolone

The acid dissociation constant (K_a) of β-isopropyltropolone (IPT or HL) together with the stability constant (K) of its chelate complex with UO₂²⁺ ion have been determined in water-ethanol medium containing 50% ethanol by volume and 0.1 M NaClO, over the temperature range 15-45°C. From these results, values of the free energy, enthalpy and entropy of the chelation have been calculated at 25°C The results are collected as follows:      

Bridged polyaromatics: Synthesis and isomorphous properties of polymers and oligomers containing O,S, CH2 bridges

A study of the isomorphous relationships existing among five crystalline polyaromatic polymers containing O, S, CH₂ bridges, i.e., where Ph is phenyl, is reported. Appropriate series of oligomers corresponding to these polymers have also been prepared in order to investigate how the solid-state properties of the oligomers correlate with those of the polymers. A preliminary x-ray analysis is reported showing that the polymers are actually isostructural.