Dihydro-1,4-benzodioxin

Cyclopenta[fc]dioxanes (44) are accessible from the reaction of the dioxenylmolybdenum carbene complex (43) with enynes <96JOC159>, whilst an intramolecular and stereoselective cyclisation of (Ti5-dienyl)tricarbonyliron(l+) cations affords chiral frans-2,3-disubstituted 1,4-dioxanes <96JOC1914>. 2,3-Dimethylidene-2,3-dihydro-1,4-benzodioxin is a precursor of the 3,8-dioxa-lff-cyclopropa[i]anthracene, which readily dimerises to dihydrotetraoxaheptacene (45) and the analogous heptaphene <96AJC533>. 

Pentafluorophenoxy)ethanol (24) reacts with potassium hydroxide to give 5,6,7,8-tetra-fluoro-2,3-dihydro-1,4-benzodioxin (25).134,135... 

RN 2165-19-7 MF C10H,3N3O2 MW 207.23 ON ((2,3-dihydro-1, 4-benzodioxin-2-yl)methyl]guanidine... 

Quaglia, W., Pigini, M., Tayebati, S.K., Piergentili, A., Giannella, M., Leonard , A., Taddei, C Melchiorre, C.. 1996. Synthesis, absolute configuration, and biological profile of the enantiomers of trans-[2-(2,6-dimethoxyphenoxy)ethyl][(3-p-tolyl-2,3-dihydro-1,4-benzodioxin-2-yl)methyl]amine (mephendioxan), a potent competitive a -adreno-receptor antagonist. J. Med. Chem. 39, 2253-2258. 

The sulfonation of 2,3-dihydro-1,4-benzodioxin (13) in concentrated sulfuric acid, and with sulphur trioxide in nitromethane or dichloromethane, has been studied <89RTC395, 92RTC183>. Nitration of (13) employing an excess of concentrated nitric acid at 20-30 °C furnished the respective... 

In the 2,3-dihydro-1,4-benzodioxin series, several approaches are available. One of the most usual is to substitute the dianion of the catechol or its derivative with a dihalogenated derivative <54JCS18, 55JA5373,93JMC1520> or with an a-chloronitrile or ester <74JOC1808>. Thus, methyl 2-chloro-2-cyclo-propylideneacetate (184) reacts with the dianion of catechol in a heterogeneous system of potassium... 

Another route uses alkyloxyphenols (188) which, when treated with various arylsulfenyl chlorides yield the corresponding 2,3-dihydro-1,4-benzodioxin derivatives (189) by intramolecular cyclization <86JPR137>. 

Thietes (thiacyclobutenes) (190) give substituted 2,3-dihydro-1,4-benzodioxins (191), when treated in dichloromethane at reflux with o-chloranil or o-bromanil <87H(26)969>. 

The 2,3-dihydro-1,4-benzodioxin ring system has aroused increasing interest, owing to its presence in a large number of structures of important therapeutic agents, the activity of which is considerably influenced by the chirality of the heterocyclic unit. Most of the syntheses of optically pure 2-substituted-2,3-dihydro-1,4-benzodioxins start from 2-hydroxymethyl-2,3-dihydro-1,4-benzodioxin in chiral form this latter compound can be obtained from D-mannitol <76CC92l>, by direct con-... 

Among the 2-phenyl-2,3-dihydro-1,4-benzodioxins, one of them, 2-(3-hydroxy-4-methoxy-phenyl)-2,3-dihydro-1,4-benzodioxin, is 450 times sweeter than sucrose, with an aftertaste similar to that of Phyllodulcin <91JCS(P2)1399). 

The 2,3-dihydro-1,4-benzodioxin framework has often been found in biologically active lignans. Silybin <75CB1482) and Americanin A <78TL3239) are antihepatotoxic, and Haedoxan <89ABC631) has insecticidal activity. 

The dioxin system (effectively a 1,2-ethenodioxy structure) is derivable from catechol and the Diels-Alder reaction shown between one such compound namely 2,3-dimethylene-2,3-dihydro-1,4-benzodioxin and methyl vinyl ketone at 70°C for 15 hours a reaction which has enabled a tricyclic compound in the series to be synthesised in 84% yield (ref. 103). 

Dihydro-1,4-benzodioxin 2,3-Dihydrobenzofuran 3,4-Dihydro-1C-2-benzopyran 3,4-Dihydro-2C-1-benzopyran 3,4-Dihydro-2W-1-benzopyran-2-one 2,3-Dihydro-4W-1-benzopyran-4-one... 

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