- Synthesis of Substituted Dibenzophospholes. Part 5. Synthesis of Intermediates for 4- and 6-Aryl Substituents
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6-Iodo-5-methoxy-8-methyl-1,2,3,4-tetrahydro-1,4-ethanonaphthalene was prepared from the Diels-Alder adduct of benzoquinone and cyclohexadiene.Diels-Alder condensation of 2-acetamimido-benzoquinone and 2-iodobenzoquinone (convenient, new syntheses of both quinones are described) with 2-methylcyclohexa-1,3-diene led to mixtures of adducts; the major adduct from the iodoquinone was isolated and found by X-ray analysis to have the methyl and iodo substituents at the 2- and 7-positions, respectively, of the 1,4-ethanonaphthalene skeleton.Addition of 2-acetamidobenzoquinone to mentha-2,6,8(9)-triene derived from (-)-carvone gave two regioisomers (structures determined by n.m.r. spectroscopy).In a smooth 4-step synthesis from 6,6-dimethylfulvene and benzoquinone, 6-iodo-9-syn-isopropyl-5,8-dimethoxy-1,2,3,4-tetrahydro-1,4-methanonaphthalene was prepared and its stucture confirmed by X-ray analysis.
- Buttrus, Nabeel H.,Cornforth, Sir John,Hitchcock, Peter B.,Kumar, Ashok,Stuart, Alan S.
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p. 851 - 858
(2007/10/02)
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- Method for preparing 2,4-diaminolphenol or 2,4-diamonophenol dihydrochloride
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A method for preparing 2,4-diaminophenol or 2,4-diaminophenol dihydrochloride comprising hydrogenation of 2,4-dinitrophenol on a membrane catalyst made of an alloy consisting of 90 to 98% by mass of palladium, 2 to 10% by mass of rhodium or ruthenium. Said hydrogenation of 2,4-dinitrophenol is effected by hydrogen diffusing through said membrane catalyst. The starting 2,4-dinitrophenol is used in a medium of water or a 4--37% aqueous solution of hydrochloric acid at a concentration of 2,4-dinitrophenol in said medium ranging from 2 to 50% by mass. The hydrogenation is effected at a temperature within the range of from 50° to 150° C. under a pressure of from 1 to 60 atm. The process is simple and performed on a simple equipment; it makes use of both pure and commercial hydrogen, enables elimination of the formation of waste waters and results in the desired products in a high yield: 2,4-diaminophenol--with a yield of up to 93%, 2,4-diaminophenol dihydrochloride--with a yield of up to 92% as calculated for the starting 2,4-dinitrophenol.
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