Synthesis and characterization of benzo[c]thiophene analogs incorporating benzo[b]thiophene/1-hexylindole/benzo[b]furan

Synthesis of 1,3-disubstituted benzo[c]thiophene analogs incorporating heterocycles such as benzo[b]thiophene/1-hexylindole/benzo[b]furan and thiophene units is described. Optical and electrochemical studies of the benzo[c]thiophene analogs are also reported.     

Synthesis of 1,3-disubstituted benzo[c]thiophene analogs containing benzo[b]thiophene/benzo[b]pyrrole

The synthesis of 1,3-disubstituted benzo[c]thiophene analogs incorporating benzo[b]thiophene/benzo[b]pyrrole units is described.     

Synthesis and characterization of 9,9-dialkylfluorene capped benzo[c]thiophene/benzo[c]selenophene analogs as potential OLEDs

The synthesis of soluble benzo[c]thiophene analogs capped with 9,9-dialkylfluorene at one end is described.     

Synthesis and characterization of 1,3-diarylbenzo[c]selenophenes

A series of 1,3-diarylbenzo[c]selenophenes (symmetrical/unsymmetrical) have been synthesized involving a selenium transfer reaction of keto-alcohol/benzo[c]furan using Woollins reagent. The optical and electrochemical studies of these diarylbenzo[c]selenophenes are correlated with their structures.     

Synthesis of 1,3-diarylbenzo[c]selenophenes

For the first time, syntheses of 1,3-diarylbenzo[c]selenophenes are reported involving a selenium transfer reaction of keto-alcohol/benzo[c]furan using Woollins reagent.     

Synthesis of end-blocked thienyl oligomers incorporating benzo[c]thiophene

A straightforward synthesis of end-capped bithienyl, quaterthienyl and sexithienyl systems incorporating benzo[c]thiophene units is presented.     

Synthesis and characterization of benzo[c]thiophene analogs tethered with dibenzo-heterocycles as potential OLEDs

Synthesis of mixed heterocyclic system containing benzo[c]thiophene, dibenzo-heterocycles, and thiophene unit is described.     

A concise synthesis of novel naphtho[a]carbazoles and benzo[c]carbazoles

Starting from simple indole precursors the synthesis of naphtho[a]carbazoles and benzo[c]carbazoles is described. Key steps include the use of the Suzuki-Miyaura reaction to afford 2- or 3-aryl substituted indoles, as well as a potassium t-butoxide and light assisted aromatic ring-forming reaction.     

Heck-like coupling and Pictet-Spengler reaction for the synthesis of benzothieno[3,2-c]quinolines

A series of 6-arylbenzothieno[3,2-c]quinolines were synthesised in three steps from benzo[b]thiophene. After a selective Heck-type coupling of benzo[b]thiophene with different o-nitroaryl bromides to obtain 2-(o-nitroaryl)benzo[b]thiophenes, corresponding 2-(benzo[b]thiophen-2-yl)anilines were involved in a Pictet-Spengler reaction to form the quinoline cycle.     

Tandem addition-cyclization of o-ethynylphenyllithiums and isoselenocyanates: a convenient preparation of functionalized benzo[c]selenophenes

The o-bromoethynylbenzenes were lithiated with tert-BuLi in Et₂O followed by treatment with isoselenocyanate, and then EtOH was added as a proton source, producing the desired (Z)-3-methylidenebenzo[c]selenophenes as the sole 5-exo-dig mode cyclization products in one-pot with yields ranging from 54-87%. The iodocyclization of the o-ethynylphenyllithium with isoselenocyanate stereoselectively gave the (E)-1′-iodo-3-methylidenebenzo[c]selenophene, which was converted into the more functionalized benzo[c]selenophenes via the Suzuki- and Sonogashira-coupling reactions.     

Acid-catalyzed condensation of 2,2′-diamino-1,1′-biaryls for the synthesis of benzo[c]carbazoles

2,2′-Diamino-1,1′-biaryls were found to undergo ring-closure condensation reaction to afford benzo[c]carbazoles in good to excellent yield. Coupled with the synthesis of 2,2′-biaryldiamines from diaryl hydrazides via [3,3]-sigmatropic rearrangement, it constitutes a new efficient synthetic method for benzo[c]carbazoles and related compounds.     

Synthesis of new benzo[b]thieno fused ring systems via transition metal-mediated cyclisations

The compact synthesis of a new ring fused benzo[b]thieno derivative with an embedded nine-membered ring system via ring closing metathesis methodology is described. The preparation of the novel 11H-benzo[b]thieno[2,3-c]pyrrolo[2,3-a]indol-11-one via palladium-mediated oxidative cyclisation of benzo[b]thien-2-oyl indole derivatives is also reported.     

1,3-Dipolar cycloaddition reactions of benzo[b]thiophene 1,1-dioxide with azomethine ylides

New pyrrolo derivatives of benzo[b]thiophene 1,1-dioxide have been synthesised via 1,3-dipolar cycloaddition reactions. Reaction of benzo[b]thiophene 1,1-dioxide with stabilised azomethine ylides gave products in low yield but high stereoselectivity whereas reaction with non-stabilised azomethine ylides gave high overall yields but low stereoselectivity.     

A facile synthesis of benzo[c]phenanthridine alkaloids: oxynitidine and oxysanguinarine using lithiated toluamide-benzonitrile cycloaddition

Benzo[c]phenanthridine alkaloids oxynitidine and oxysanguinarine were synthesized from easily available starting benzonitrile 5 and toluamide 6 using toluamide-benzonitrile cycloaddition reaction in six steps. This method is so highly efficient that it could be a more useful way for preparing fully aromatized benzo[c]phenanthridine compounds.     

Convenient synthesis of fused pyrano[3,2-h]- and furo[3,2-h]benzo[f]coumarins from naphthalene-2,3-diol

The treatment of 8-propargyloxy-benzo[f]coumarin with boron trifluoride diethyl etherate in N,N-dimethylformamide under reflux or MW irradiation resulted in pyrano[3,2-h]benzo[f]coumarin, while the furo[3,2-h]benzo[f]coumarin is received from the treatment with N-methylformamide under MW irradiation.     

Synthesis of novel fluorescent benzo[a]pyrano[2,3-c]phenazine and benzo[a]chromeno[2,3-c]phenazine derivatives via facile four-component domino protocol

An efficient and practical route to novel fluorescent benzo[a]pyrano[2,3-c]phenazine framework has been developed by one-pot, four-component reaction of 2-hydroxynaphthalene-1,4-dione, 1,2-phenylenediamines, aromatic aldehydes, and Meldrum’s acid in glacial acetic acid at 70 °C. Photophysical studies of these compounds have been reported. Reactions involving cyclohexane-1,3-dione/5-methylcyclohexane-1,3-dione/dimedone in the place of Meldrum’s acid yielded corresponding benzo[a]chromeno[2,3-c]phenazine derivatives. Crystal structure of 3k established the regioisomer formed. Mild reaction conditions, good yields, short reaction time, and easy separation are some of the salient features of the present protocol.     

Synthesis of benzo[c]fluorenone through a one-pot cascade reaction using inden-1-one derivatives

A novel one-pot thermal cycloaddition of two indenones followed by a decarbonylation and dehydrogenation cascade afforded benzo[c]fluorenones regioselectively. Various substituted indenone derivatives were converted into their corresponding benzo[c]fluorenones in good to excellent yields.     

Synthesis of 1,3-diaryl benzo[c]thiophenes

An array of 1,3-diarylbenzo[c]thiophenes has been synthesized via the ring opening of lactones followed by thionation using Lawesson’s reagent.     

The synthesis of benzo[b]phenanthro[d]thiophenes and anthra[b]benzo[d]thiophenes

The synthesis of benzo[b]phenanthro[2, 3-d]thiophene ( 5 ), benzo[b]phenanthro[4, 3-d]thiophene ( 6 ), benzo-[b]phenanthro[2, 1-d]thiophene ( 9 ), benzo[b]phenanthro[3, 2-d]thiophene ( 14a ), anthra[1, 2-b]benzo[d]thiophene ( 24 ), anthra[2, 3-b]benzo[d]thiophene ( 29 ) and anthra[2, 1-b]benzo[d]thiophene ( 30 ) is described as well as the preparation of 13-methylbenzo[b]phenanthro[3, 2-d]thiophene ( 14b ).     

Formation of benzo[c]thiophen-1-aminium iodide by the reaction of o-alkynylbenzothioamide with iodine

Reaction of o-alkynylbenzothioamide with molecular iodine was investigated. Unique benzo[c]thiophen-1-aminium iodide was obtained when the tertiary thioamide was used as a reactant. The reaction proceeded efficiently in less polar solvent, whereas the corresponding product was also obtained in a polar solvent. Single crystal X-ray analysis revealed that the benzo[c]thiophen-1-aminium structure possesses a resonance structure in N–C–S bond. Its stabilization shows a clear difference in the result from the reaction of amide analogue with iodine to give no stable compound.