Pyrimidine to guanine PDE inhibitors: determination of chemical course via structure elucidation

Structure elucidation of several new pyrimidines containing a varying extent of hydrogen bonding allowed for determination of the course of chemical reactions towards the preparation of novel substituted pyrimidines.     

A facile synthesis of novel tricyclic 4-pyridones

A new and efficient synthesis of tricyclic 4-pyridone analogs through the intramolecular Heck coupling cyclization was described. This reaction features mild conditions and good functional group tolerance allowing for the preparation of several novel tricyclic 4-pyridone analogs.     

A novel approach to synthesis of tricyclic diterpenoid

A novel approach has been found and the first total synthesis of (±)-Salvirecognine was accomplished by using it. In which intramolecular cyclization and Friedel-Crafts alkylation took place simultaneously to afford key intermediates for synthesis of aromatic tricyclic diterpenoids.     

Efficient synthesis of novel tricyclic fused pyranothiazolopyrimidine derivatives via isocyanide-based three-component reactions

An efficient and facile one-pot synthesis is described for the preparation of novel tricyclic fused pyranothiazolopyrimidines containing both biologically active thiazolopyrimidine and pyranopyrimidine templates via three-component reaction involving an isocyanide with a dialkylacetylenedicarboxylate (DAAD) and 2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidine-5,7(6H)-dione, in high yields.     

A simple one pot synthesis of novel tricyclic quinazolinones

Synthesis of a series of tricyclic quinazolinones have been accomplished starting from anthranilamide and 1,3-cyclic dione promoted by TsOH·H₂O The protocol presented herein based on retro-Dieckmann type reaction, leading to incorporation of dione as an acyclic unit into the product. Simple reaction conditions, broad scope, excellent yields are the advantages of this protocol. Further, this methodology is extended to the synthesis of pyridopyrimidinones and benzimidazopyridines.     

One-step synthesis of novel tricyclic isomeric azidonucleosides

Several tricyclic azido-isonucleosides were formed in high yields by the treatment of pyrimidine isonucleosides with triphenylphosphine, tetrabromomethane, and sodium azide. The regioselective ring opening of these tricyclic azido-isonucleosides was also investigated.     

Flow microreactor synthesis of tricyclic sulfonamides via N-tosylaziridinyllithiums

Tricyclic sulfonamides were synthesized by the generation of aziridinyllithiums from N-tosylaziridines followed by an intramolecular nucleophilic reaction and the subsequent reaction with electrophiles using a flow microreactor system. The reactions could be carried out at 0 °C, although much lower temperatures such as ?78 °C are needed for batch macro reactors.     

Total synthesis of the novel tricyclic sesquiterpene sulcatine G

A synthetic approach to the tricyclic sesquiterpene sulcatine G, 2, bearing a novel tricyclo[6.2.0.2(2,6)]decane framework, from commercially available 1,5-cod and leading to the first total synthesis of the natural product is described.     

Asymmetric synthesis of tricyclic tetralin derivatives via an intramolecular photoreaction

An intramolecular photoreaction for the synthesis of tricyclic tetralin derivatives through a Norrish/Yang type cyclization is described. Asymmetric studies on this reaction using ionic chiral auxiliaries gave enantiomeric excesses of up to 99% at conversions of 80%, and the reaction mechanism was mapped out by a single crystal-to-single crystal reaction.     

Synthesis of novel tricyclic pyrimidine-fused 5,6-dihydrobenzodiazepines via a Pictet-Spengler-like cyclization

Novel pyrimidine-fused 5,6-dihydrobenzodiazepines were prepared via a Pictet-Spengler-like cyclization. It was based on the intramolecular electrophilic substitution of the phenyl ring of 5-amino-6-chloro-4-(N-methylanilino)pyrimidine 1 by the iminium intermediate formed with an aldehyde in one pot. The products may be further transformed by subsequent nucleophilic substitution of the chloro atom. This strategy may provide an efficient method to access a library of compounds based on privileged substructures that are of interest in drug discovery.     

A convenient synthesis of tricyclic purine derivatives

A convenient synthesis of new heterocycles such as 7,8-dihydro-1H-imidazo[2,1-i]purin-5(4H)-ones ( 2 , n = 0) and 5,6-dihydro-1H-imidazo[2,1-b]purin-9(8H)-ones ( 3 ) was described. The syntheses of 2 and 3 were accomplished by treatment of 6-methylthio-7H-purin-2(3-H)-ones 7 or 2-benzylthio-1-methyl-9-triphenylmethyl-9H-purin-6(1H)-one ( 15 ) with appropriate aminoalcohol followed by dehydrative cyclization using thionyl chloride. Compound 15 was efficiently prepared by benzylation of 6-hydroxy-2-mercaptopurine ( 12 ) followed by tritylation and N-methylation.     

A novel one-pot, three-component reaction: formation of tricyclic 1,2-dihydropyridines via mesomeric betaines

A one-pot, three-component reaction of pyridine, thiophthalimide and acyl chloride gives novel tricyclic 1,2-dihydropyridines regio- and stereoselectively, in which a mesomeric betaine would be a key intermediate for [4+2]-cycloaddition reaction with thiocarbonyl compounds.     

A novel synthesis of tetrahydrofuran via alkoxy radical cyclisation

Tetrahydrofurans were synthesised via 5-exo-trig cyclisation of alkoxy radical generated by unprecedented 1,5-hydrogen shift from hydroxyl group to vinyl radical.     

A novel synthesis of quinolinium salts via benzotriazole methodology

A novel method for the synthesis of 1,4- and 1,3,4-substituted quinolinium salts and 1,2,4- and 1,2,3,4-substituted-1,2-dibydroquinolines from N-substituted-N(benzotriazol-1-ylmethyl)aniline derivatives is reported.     

A novel one-pot two-component synthesis of tricyclic pyrano[2,3-b]quinoxalines

A one-pot two-component synthesis of tricyclic pyrano[2,3-b]quinoxalines with a pendant hydroxymethyl fuction at the 2-position relevant to molybtopterin is described by the reaction of o-phenylenediamine and phenylhydrazone derivatives of sugars in good yields.     

Stereoselective synthesis of highly functionalised tricyclic β-lactams via intramolecular nitrilimine cycloaddition

The novel azeto[2′,1′:1,2]pyrrolo[3,4-c]pyrazole skeleton has been obtained in both racemic and enantiopure forms by means of intramolecular cycloaddition of nitrilimines 6. Fully stereoselective cycloadditions were obtained, giving tricyclic β-lactams 7 as single diastereoisomers with good overall yields.     

A novel one-pot pyrrole synthesis via a coupling-isomerization-Stetter-Paal-Knorr sequence

[reaction: see text]. 1,2,3,5-tetrasubstituted pyrroles can be synthesized in good yields in a one-pot, three-step, four-component process by a coupling-isomerization-Stetter reaction-Paal-Knorr sequence of an electron-poor (hetero)aryl halide, a terminal propargyl alcohol, an aldehyde, and a primary amine. The structures of the 1,4-diketone 4f and the pyrrole 6b were additionally supported by X-ray structure analyses.     

A facile synthesis of enantiopure tricyclic furanyl and pyranyl derivatives via tungsten-mediated cycloalkenation and Diels-Alder reaction

We report the synthesis of chiral furanyl and pyranyl dienes 1 and 2 based on cycloalkenation of chiral tungsten alkynol complexes. These two dienes bear a chiral 1,3-dioxolane group to control diastereoselective Diels-Alder reactions with electron-deficient olefins. The chiral 1,3-dioxolane substituents of the cycloadducts were degraded into hydrogen atoms to make these molecules possess common furan and pyran rings. Dienes 1 and 2 are good building blocks for enantiopure forms of tricyclic oxygen compounds.     

One-pot multicomponent synthesis and antimicrobial evaluation of novel tricyclic indenopyrimidine-2-amines

The synthesis of novel tricyclic indenopyrimidine-2-amines from 3,3-dimethyl-/3-methyl-2H-indanones has achieved by base-catalyzed one-pot three-component reaction. The desired products are formed within 10 hours after addition at reflux temperature. This multicomponent approach offers a viable protocol for the construction of indenopyrimidine-2-amines in single-step without the isolation of the intermediates 3,3-dimethyl/3-methyl-2-(4-substituted benzylidene)-2,3-dihydro-1H-inden-1-ones. All the synthesized compounds have been screened for antimicrobial activity and some of the derivatives show comparable activity against bacterial and fungal isolates.