The synthesis of cis-6,12-Diaryl-6H,12H-dibenzo[b,f][1,5]dithiocin-6,12-imine and cis-6,12-Diphenyl-6,12-epoxy-6H,12H-dibenzo[b,f][1,5]dithiocin

When treated with concentrated hydrochloric acid or heated beyond its melting point, the versatile thioimine 2 2-mercaptobenzhydrylidenamine was unexpectedly converted to the title ring system. Also, this imine can be converted to 3-phenyl-1,2-benzisothiazoles by prolonged exposure to air.     

A facile synthesis of 2,4,8,10-tetrahalo-6,12-diaryldibenzo[b,f][1,5]diazocines

3,5-Dihalo-2-aminobenzophenones 2 on prolonged reflux in dry pyridine gave 2,4,8,10-tetrahalo-6,12- diaryldibenzo[b,f][1,5]diazocines 3 in high yields. Attempted condensation of 2 with glycine ester hydrochloride under identical reaction conditions failed to afford 1,4-benzodiazepines.     

Microwave assisted synthesis of indolo[2,3-b]dibenzo[b,g][1,8]naphthyridines

We have developed an effective microwave assisted p-TsOH catalyzed synthesis of indolo[2,3-b]dibenzo[b,g][1,8]naphthyridines via a one pot reaction of 3-amino-9-ethylcarbazole and 2-chloro-3-formylquinolines.     

An efficient synthesis of 1-oxo-1,2-dihydrobenzo[b][1,6]naphthyridine-4-carbonitriles

Ethyl α-(dimethylaminomethylene)-2-cyanomethyl-4-phenylquinoline-3-carboxylate(2) as new synthons directed to 1-oxo-1,2-dihydrobenzo[b][1,6]naphthyridine-4-carbonitriles was obtained by the condensation of ethyl 2-cyanomethyl-4-phenylquinoline-3-carboxylate(1) and N,N-dimethylformamide dimethyl acetal(DMFDMA).Reaction of this enamine with primary amines(3) in HOAc-DMF at120 ℃then affords 2-substituted 1-oxo-1,2-dihydrobenzo[b][1,6]naphthyridine-4-carbonitrile derivatives(4) in good yields by a tandem addition-elimination-cyclization reaction.     

Eight-membered organosulfur heterocycles. Synthesis of dibenzo[d,g][1,3,6,2]dioxathiaphosphocin and dibenzo[d,g][1,3,6,2]dioxathiasilocin ring systems

The reaction of 2,2′-thiobisphenols with either phenylphosphonous dichloride or phosphorus trichloride followed by an alcohol gave derivatives of the dibenzo[d,g][1,3,6,2]dioxathiaphosphocin ring system. The analogous reaction of 2,2′-thiobisphenols with alkyl and aryl dichlorosilanes gave the heretofore unreported dibenzo[d,g][1,3,6,2]dioxathiasilocin ring system. The analytical and spectral data are reported.     

A novel synthesis of dibenzo[b,f] [1,4]thiazepin-11(10H)one 5,5-dioxides

Treatment of thioxanthen-9-one 10,10-dioxides with sodium amide in liquid ammonia provided a novel one-step conversion to dibenzo[b,f][1,4]thiazepin-11(10H)one 5,5-dioxides. Some limitations and a possible mechanism for the reaction are discussed.     

Distinct difference of chemical behaviors between 5H,7H-dibenzo[b,g][1,5]dithiocin 12-oxide and thiazocine S-oxide

5H, 7H-Diobenzo [b,g] [1,5] dithiocin 12-oxide (2) rearranged into 6-oxide (3) in the presence of CF₃CO₂H. The corresponding thiazocine S-oxide (5) was only protonated at the amino group under the same conditions. Furthermore, methylation of 2 afforded S-methylated product (7) in contrast to O-methylated product in 5.     

Synthesis of dibenzo[b,f][1,4]oxazepin-11(10H)-ones from 2-nitrobenzoic acids

Base-catalyzed intramolecular nucleophilic substitution for the 2-nitro group in 2-hydroxyanilides of 2-nitrobenzoic acids gave dibenzo[b,f][1,4]oxazepin-11(10H)-ones. In particular, 3-nitrodibenzo[b, f][1,4]oxazepin-11(10H)-one was obtained from N-(2-hydroxyphenyl)-2,4-dinitrobenzamide. The nitro group in the product could also be replaced under the action of O- and S-nucleophiles. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 529–533, March, 2006.     

Electron transfer from dibenzo[b,f]-1-azapentalene dianion: Attempted synthesis of dibenzo[b,f]-1-azapentalene

When dibenzo[b,f]-1-azapentalene dianion (3) was allowed to react with either iron (III) chloride or ethylene bromide, a one-electron transfer from3 took place readily to give the radical anion11. Further electron transfer from11 did not occur presumably due to the antiaromatic character of dibenzo[b,f]-1-azapentalene (1) that would have resulted. The radical anion11 underwent further transformation by hydrogen abstraction from the solvent to give 5,10-dihydroindeno[1,2-b]indole (2) and by dimerization to themeso and (R,S) isomers of 5,5,10,10-tetrahydro-10,10-biindeno[1,2-b]indole (4 a and4 b) respectively.

---

Elektronentransfer von Dibenzo[b,f]-1-azapentalen-Dianion: Ein Versuch zur Synthese von Dibenzo[b,f]-1-azapentalen

Zusammenfassung Die Reaktion von Dibenzo[b,f]-1-azapentalen-Dianion (3) mit Eisen (III) oder Ethylenbromid ergab einen Ein-Elektronentransfer zum Radikalanion11. Ein weiterer Elektronentransfer fand nicht statt, vermutlich wegen des antiaromatischen Charakters von Dibenzo[b,f]-1-azapentalen (1), das dabei entstehen müßte. Das Radikalanion11 ergab unter Wasserstoffentzug aus dem Lösungsmittel 5,10-Dihydroindeno[1,2-b]indol (2), das weiter zummeso- bzw. (R,S)-5,5,10,10-tetrahydro-10,10-biindeno[1,2-b]indol (4 a bzw.4 b) dimerisierte.

     

One-pot synthesis of new 6-(alkylamine)dibenzo[c,e][1,2]oxaphosphinine-6-oxides

Several new 6-(alkylamine)-6H-dibenz[c,e][1,2]oxaphosphinine-6-oxides were prepared through a one-pot reaction, starting with 2-phenylphenol, phosphorus trichloride, and a Zn catalyst, to form 6-chloro-6H-dibenz[c,e][1,2]oxaphosphine. The alkylamine derivatives were subsequently prepared through a nucleophilic substitution reaction involving aliphatic amines and H₂O₂ oxidation under soft conditions. This method has the advantages that it is a one-pot synthesis, does not require an inert atmosphere, and involves in situ catalyst formation.     

1H-pyrrolo[3,2-c]pyridin-4,6(5H,7H)dione(3,7-dideazaxanthine)

A facile chemical synthesis of 1H-pyrrolo[3,2-c]pyridin-4,6(5H,7H)dione (3,7-dideazaxanthine) has been accomplished from ethyl 3-ethoxycarbonylpyrrole-2-acetate.     

Synthesis of new tetrahydrobenzo[b]pyrimido- [5,4-g][1,8]naphthyridine-2,4-diones from 6-aminouracils

Russian Journal of Organic Chemistry - Cyclocondensation of N-substituted 6-aminouracils with 3- and 7-methyl-2-iodoquinoline-3-carbaldehydes gave the corresponding 12- or 9,12-substituted...     

Phenanthrene-fused azo-ene-ynes: synthesis of dibenzo[f,h]cinnoline and dibenzo[e,g]isoindazole derivatives

The cyclization reactions of a phenanthreno-fused azo-ene-yne compound have been studied both experimentally and computationally. Experimental results show that this system is prone to dimerization, more so than previously studied naphthalene- and benzene-based analogues. Calculations reveal that pyrazoles and arene-fused pyrazoles strongly stabilize carbenes in the 5-position through "coarctate conjugation", suggesting a stationary concentration of the carbenes/carbenoids during cyclization that is high enough for dimerization.