Cu2O-catalyzed tandem ring-opening/coupling cyclization process for the synthesis of 2,3-dihydro-1,4-benzodioxins

2,3-Dihydro-1,4-benzodioxins can be prepared in a tandem one-pot procedure by reaction of o-iodophenols with epoxides catalyzed by Cu2O/1,10-phenanthroline/Cs2CO3 system. The reaction is suggested to occur via a novel ring-opening/coupling mechanism, giving moderate to good yields. Moreover, both aryl and aliphatic epoxides are tolerated under these conditions.     

Synthesis of novel aza analogues of 2-substituted-2,3-dihydro-1,4-benzodioxins as potential new scaffolds for drug discovery

New synthesis approaches that have led to a series of novel aza analogues of the 2-substituted-2,3-dihydro-1,4-benzodioxin core, bearing versatile bromomethyl group on the non aromatic oxygenated ring, are described. According to their structures these novel scaffolds can be useful intermediates for the preparation of potential new therapeutic agents.     

Efficient synthesis of 2,3-dihydro-1,4-benzoxazines via intramolecular copper-catalyzed O-arylation

A highly efficient synthetic approach to 2,3-dihydro-1,4-benzoxazines is described. The method involves a mild intramolecular copper-catalyzed O-arylation of β aminoalcohol, which works well without N-protection.     

Phosphorylation of 2-methylbenzofuran and 2,3-dihydro-2-methylene-1,4-benzodioxin

The reaction of 2-methylbenzofuran and 2,3-dihydro-2-methylene-1,4-benzodioxin with phosphorus tribromide in alkaline media was used to produce the corresponding dibromophosphines, and other phosphorylated derivatives of these heterocyclics were produced on the basis of them.Ukrainian State Chemico-Technological University, Dnepropetrovsk 320005. Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kiev 253094. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 310–316, March, 1995. Original article submitted February 6, 1995.     

Reaction of dichlorocarbene with 2,3-dihydro-5,6-dimethyl-1,4-oxathiin and 2,3-dihydro-5,6-dimethyl-1,4-dithiin

Dichlorocarbene, generated from ethyl trichloroacetate and sodium ethoxide, reacts with 2,3-dimethyl-5,6-dihydro-1,4-oxathiin to give 7,7-dichloro-1,6-dimethyl-2-oxa-5-thiabicyclo[4,1,0]heptane, and with 2,3-dimethyl-5,6-dihydro-1,4-dithiin to give 6-chloro-2,3-dihydro-7-methyl 5-methylene-5(H)-1,4-dithiepin. Both products were oxidised to the corresponding sulfone.     

Mass spectra of 1H-2,3-dihydro-1,4-benzodiazepine-2-thiones

The mass-spectrometric fragmentation of 1H-2,3-dihydro-1,4-benzodiazepine-2-thiones differs substantially from the fragmentation of the corresponding oxo derivatives with respect to the presence of [M - HCN]⁺ and [M - SH]⁺ ions. This is due to the tautomeric transformation of the molecular ions of the thiones to enethiol and eniminothiol tautomeric forms. The approximate percentages of each of the tautomeric forms were estimated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1412–1417, October, 1976.     

Synthesis of 2-(2-imidazolinyl) substituted 2,3-dihydro-4H-1,4-benzothiazine and 3,4-dihydro-2H-1,4-benzoxazines

An investigation into the synthesis of benzoxazine, benzoxathiane and benzothiazine derivatives of 2-(2-imidazolinyl)-1,4-benzodioxane has been carried out.     

On the reaction of α-(2-hydroxyphenoxy)alkylketones with dimethylsulphoxonium methylide. A novel route to 2-substituted-2,3-dihydro-2-hydroxymethyl-1,4-benzodioxins

A new route to 2-substituted-2,3-dihydro-2-hydroxymethyl-1,4-benzodioxins 3 based on the reaction of α-(2-hydroxyphenoxy)alkylketones 1 with dimethylsulphoxonium methylide in dimethylsulphoxide is reported. Besides the desired compounds 3 , the isomeric 2H-3,4-dihydro-1,5-benzodioxepines 4 were also isolated, generally as minor products. The concurrent formation of 3 and 4 has been interpreted as occurring through the intermediate oxiranes 2 , which can undergo intramolecular nucleophilic attack at either of the carbon atoms of the epoxy ring.     

A convenient synthesis of 3,4-dihydro-1,4-benzoxazin-2-ones

3,4-Dihydro-1,4-benzoxazin-2-one was prepared for the first time by catalytic hydrogenation of 4-benzyl-3,4-dihydro-1,4-benzoxazin-2-one. A simple and efficient synthesis of 4-benzyl- and 4-alkyl-3,4-dihydro-1,4-benzoxazin-2-one derivatives from ethyl 2-(2-hydroxyphenylamino)acetate and aldehydes is described. Some considerations regarding the reactivity of 3,4-dihydro-1,4-benzoxazin-2-ones are given.     

Heterogenous-catalytic synthesis of 2,3-dihydroselenophene and 3,4-dihydro-2H-selenopyran

A heterogenous-catalytic synthesis of 2,3-dihydroselenophene and 3,4-dihydro-2H-selenopyran was carried out. It was based on selenation of the corresponding oxygen-containing heterocycles on zeokar-2 and aluminum oxide as catalysts.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1478–1480, November, 1986.     

Synthesis of 5,6-dihydro-2H-thiins and 2,3-dihydro-1,4-oxathiins based on 1-benzylsulfonyl-1,1-dihydropolyfluoroalkan-2-ones

1-Benzylsulfonyl-1,1-dihydropolyfluoroalkan-2-ones react with phthalimidosulfenyl chloride or succinimidosulfenyl chloride to form the sulfenylated products on the active methylene group, 1-benzylsulfonyl-1-phthalimido(succinimido)thiopolyfluoroalkan-2-ones. Decomposition of the latter leads to formation of 1-benzylsulfonyl-1-thioxopolyfluoroalkan-2-ones. These compounds easily undergo the hetero Diels-Alder reaction with electron-rich 1,3-dienes as dienophiles and with electron-rich olefins as hetero-1,3-dienes. Polyfluoroalkyl substituted derivatives of six-membered sulfur-containing heterocycles, 5,6-dihydro-2H-thiins and 2,3-dihydro-1,4-oxathiins, are obtained as a result of these reactions.     

Mass spectra of 3-arylidene-1H-2,3-dihydro-1,4-benzodiazepin-2-ones

The scheme of the fragmentation of arylidene derivatives of 5-phenyl-1,4-benzodiazepin-2-ones was established by means of high-resolution mass spectrometry. One of the principal fragmentation pathways of these compounds is cleavage of the 2C-3C and 4N-5C bonds to give two fragments. Depending on the substituents in the arylidene portion of the molecule, the charge is localized primarily on one or the other of these fragments. The mechanism of the formation of the [ArCH₂]⁺ ions observed in the mass spectra of all of the investigated compounds was established on the basis of the mass spectrum of the 1N-deuterium-labeled compound. The specific fragmentation pathways due to the ortho effect of the nitro group are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1690–1696, December, 1976.     

A rearrangement in the reaction of 2-bromomethyl-1,3-thiaselenole with ethanol: synthesis of 2-ethoxy-2,3-dihydro-1,4-thiaselenine

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