Biginelli‐like three component reaction: Synthesis of some new ethyl 6‐ethoxycarbonylmethyl‐4‐aryl‐2‐oxo‐1,2,3,4‐tetrahydropyrimidine‐5‐carboxylate derivatives

In the context of our high‐throughput organic synthesis program, we have studied the reactivity of special β‐keto esters toward the Biginelli reaction. We have found that a diethyl‐3‐oxoglutarate reacts with one molecule of urea and one molecule of aldehyde under solvent‐free conditions to give a new family of 3,4‐dihydropyrimidin‐2(1H)‐ones in good yields.     

Gas‐phase pyrolysis in organic synthesis: New route for synthesis of functionally substituted imidazoles

1,2,3‐Triazolylpropanone was prepared and coupled with aryldiazonium salts yielding the corresponding arylhydrazones. Gas‐phase pyrolysis of the hydrazono derivative produced N‐arylamino‐2‐acetylimidazole as well as 2‐acetylimidazole. The latter is the product of further pyrolysis of the former.     

Synthesis and reactions of the thioamide derivatives of methyl vinyl ketone

The reaction of isothiocyanates with in situ generated carbanions of α,β‐unsaturated ketones yielded α,β‐unsaturated keto thioamides which in the reaction with acids or bases cyclized to give 2,6‐disubstituted thiopyran‐4‐ones and in the reaction with α‐bromoesters gave thiazolidin‐4‐one derivatives. The thiopyran‐4‐ones reacted with α,β‐unsaturated aldehydes to yield tetrahydrothiopyran[2,3‐b]pyridin‐4‐ones, while thioanilides were formed in the reaction with phenyl isothiocyanate.     

Synthesis of 2,2′‐bipyridyl‐type compounds via the suzuki‐miyaura cross‐coupling reaction

2,2′‐Bipyridyl‐type compounds may be prepared by Suzuki‐Miyaura coupling of a 2‐pyridylboronic ester with 2‐haloazines and ‐azoles. Ten examples are presented with yields of 47 to 84%. Both arylbromides and arylchlorides undergo the coupling, but the reaction is sensitive to ring substitution adjacent to the halogen.     

Metathetic approach towards macrocyclic bis‐ethers and in sequence use of barbier reaction and RCM for spirocyclic ethers

An efficient method for the synthesis of novel macrocyclic bis‐ethers from alizarin and also some new spiro ethers from various substituted ketones by the use of Barbier and ring‐closing metathesis (RCM) reactions has been developed.     

Solvent‐free synthesis of 5‐methyl‐7‐aryl‐4,7‐dihydrotetrazolo[1,5‐a]pyrimidine‐6‐carboxylic esters catalyzed by sulfamic acid

The solvent‐free synthesis of 5‐methyl‐7‐aryl‐4,7‐dihydrotetrazolo[1,5‐a]pyrimidine‐6‐carboxylic esters was performed and effectively catalyzed by sulfamic acid. Compared with conventional methods, this protocol features mild reaction conditions and high yields. Furthermore, it is solvent‐free and thus eco‐friendly.     

Application of the acetate of baylis‐hillman adducts of salicylaldehydes in the synthesis of methyl 2‐oxo‐2,3‐dihydrobenzo[b]oxepine‐4‐carboxylates

A simple synthesis of several methyl 2‐oxo‐2,3‐dihydrobenzo[b]oxepine‐4‐carboxylates from Baylis‐Hillman adducts of O‐benzyl protected 2‐hydroxybenzadehydes has been described through the acetylation, cyanation, debenzylation, as well as acid assisted Pinner cyclization.     

Synthesis of some novel 2,6‐disubstituted pyridazin‐3‐ones as TMC120 analogues

Different analogues of TMC120 derived from pyridazin‐3(2H)‐one rings were synthesized by coupling of 3,6‐dichloropyridazine with arylacetonitriles, phenols and/or aniline derivative followed by hydrolysis and alkylation with different benzyl bromide derivatives.     

Synthesis of a novel diazepine

A novel pyrrolopyridodiazepine ring system was synthesized from methyl 2‐methyl nicotinate.     

Synthesis of novel 3,4‐diaryl‐1H‐pyrroles

The synthesis of a series of novel 3,4‐diaryl‐1H‐pyrroles and related arylalkenes from p‐bromo thiophenol, tosylmethyl isocyanide and commercially available materials is reported. Arylalkenes having electron‐withdrawing substituents gave higher yield of 3,4‐diaryl‐1H‐pyrroles.     

One‐pot synthesis of pyrido[2,3‐d]pyrimidines via efficient three‐component reaction in aqueous media

A short and facile synthesis of pyrido[2,3‐d]pyrimidine derivatives was accomplished in good yields via the three‐component reaction of aldehydes, alkyl nitriles and aminopyrimidines in water in the presence of triethylbenzylammonium chloride (TEBAC). The structures of these compounds were characterized by elemental analysis, IR and ¹H NMR spectra and further confirmed by single crystal X‐ray diffraction analysis.     

Synthesis,structures of some unsymmetrical 3,6‐disubstituted‐1,2,4,5‐tetrazines

A series of new unsymmetrical 3‐phenyl‐6‐benzyl‐1,2,4,5‐tetrazine derivatives 10a‐i were synthesized and characterized by IR, NMR, MS, and element analysis. The structures of 4a, 10c, 10d and 10h were analyzed by X‐ray crystallography, which had intermolecular C‐H‐N, C‐H‐Cl, C‐H‐II and II‐II interactions.     

Design and synthesis of new and significative bifunctional compounds containing two pyrazolo[3,4‐b]pyridine nucleis through multicomponent reaction under microwave irradiation

A series of new and significative bifunctional compounds containing two pyrazolo[3,4‐b]pyridine moieties has been synthesized through a rapid one‐pot three‐component reaction of dialdehyde, 5‐amino‐3‐methyl‐1‐phenylpyrazole and active methylene compounds in glycol under microwave irradiation without catalyst. The method has the advantages of good yield (85‐98%), short route and reaction time (45‐300s), wide reaction scope and easy work‐up procedure.     

Regioselective cyclodehydration of ortho‐hydroxy acetyl aryloxyketones to benzofuran

ortho‐Hydroxy acetyl benzofuran derivatives have been synthesized in a regioselective cyclodehydration of aryloxyketones obtained from β‐resacetophenone and α‐halo ketones.     

Investigation of sp2–sp Coupling for Electron‐Enriched Aryl Dihalides under Oxygen‐Free Sonogashira Coupling Reaction Conditions Using a Two‐Chamber Reaction System

Triethylamine hydroiodide crystals were formed during Sonogashira reactions; after complete reaction the solution retains a characteristic light color (see picture). Very sluggish Sonogashira reactions of electron‐enriched aryl diiodides have been carried out in high yield in an oxygen‐free, two‐chamber reaction system. The formation of triethylamine hydroiodide crystals was monitored to determine the completion of reaction.

     

Phenacylsulfonylacetic acid methyl ester‐synthon for 1,2,3‐selena/thiadiazoles and 2H‐diazaphospholes

A new class of 1,2,3‐selena/thiadiazoles and 2H‐diazaphospholes were synthesized by exploiting α‐ketomethylene group in phenacylsulfonylacetic acid methyl ester.