Showing papers on "Boron tribromide published in 1992"
TL;DR: Naloxone as discussed by the authors was obtained by demethylation of N-allylnoroxycodone 1 with methane sulfonic acid / methionine, which is an excellent substitute for boron tribromide.
28 citations
TL;DR: The crystal structure of the monoacetone solvate of the nickel(II) perchlorate derivative of the 14-membered trans-P 2 S 2 chelating macrocycle has been determined as discussed by the authors.
Abstract: The R * ,R * and R * ,S * forms of the 14-membered trans-P 2 S 2 chelating macrocycle 5,6,7,9,14,15,16,18-octahydro-5,14-dimethyldibenzo[e,l] [1,8,4,11]dithiadiphosphacyclotetradecin have been isolated in low yields from the dimerization of deprotonated (±)-(2-mercaptoethyl)(2-methoxybenzyl)methylphosphine on platinum(II) in the presence of boron tribromide. The crystal structure of the monoacetone solvate of the nickel(II) perchlorate derivative of the R . ,R . diastereomer of the macrocycle has been determined.
25 citations
Patent•
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24 Feb 1992
TL;DR: In this paper, a C-Br polymer layer is formed on the surface of a resist pattern as usual and high selectivity is obtd, but side etching is avoided.
Abstract: PURPOSE:To accurately dry-etch Al (alloy) without side etching by mixing etching gas consisting of gaseous boron tribromide and gaseous chlorine with gaseous hydrogen. CONSTITUTION:Al (alloy) is dry-etched with a gaseous mixture of gaseous boron tribromide and gaseous chlorine with gaseous hydrogen as etching gas. Chlorine molecules, bromine molecules, chlorine radicals and bromine radicals causing the side etching of Al (alloy) react with hydrogen and become hydrogen chloride molecules and hydrogen bromide molecules. These hydrogen chloride and hydrogen bromide have low reactivity with Al (alloy) in the state of neutral radicals and do not cause side etching. A C-Br polymer layer is formed on the surface of a resist pattern as usual and high selectivity is obtd.
23 citations
TL;DR: A new synthesis of the highly efficient, selective dopamine D2 agonist, 2-fluoro-N-propylnorapomorphine 1 has been accomplished, involving the transformation of thebaine 13 into 6-fluororo-6-demethoxythebaine 10 and subsequent O-demethylation with boron tribromide.
Abstract: A new synthesis of the highly efficient, selective dopamine D2 agonist, 2-fluoro-N-propylnorapomorphine 1 has been accomplished, involving the transformation of thebaine 13 into 6-fluoro-6-demethoxythebaine 10, followed by sequential N-demethylation, N-alkylation, rearrangement with methanesulfonic acid into the apocodeine derivative 17, and subsequent O-demethylation with boron tribromide.
17 citations
TL;DR: In this article, carboxylic acids are converted into acid bromides on alumina which has been modified with boron tribromide and a different reaction occurs in solution.
8 citations
Patent•
11 Dec 1992TL;DR: In this paper, 2,2-bis[4-hydroxyphenyl)-phenyl]alkanes are prepared by the reaction of a bisphenol A ester or a similar compound with a p-trialkyltin-substituted anisole, followed by demethylation with a Lewis acid such as boron tribromide.
Abstract: Bis[4-(4-hydroxyphenyl)-phenyl]alkanes, as illustrated by 2,2-bis[4-(4-hydroxyphenyl)-phenyl]propane, may be prepared by the reaction of a bisphenol A ester or a similar compound with a p-trialkyltin-substituted anisole, followed by demethylation with a Lewis acid such as boron tribromide. Polycarbonates prepared therefrom are ductile and have high glass transition temperatures.
8 citations
TL;DR: In this article, the synthesis of 7-hydroxy-5-isopropyl-3,8-dimethylnaphthalene-1,2-dione was reported, which was found to be identical with the natural product azanzone A, thus confirming the structure of the latter.
Abstract: The synthesis is reported of 7-hydroxy-5-isopropyl-3,8-dimethylnaphthalene-1,2-dione 2 which was found to be identical with the natural product azanzone A, thus confirming the structure of the latter. The synthesis was achieved using the Stobbe condensation to obtain the butanedioic acid mono-ester 8 which readily cyclised to give the naphthoate 9. Reduction of the ester to a methyl group, followed by Fremy's salt oxidation and O-demethylation with boron tribromide completed the synthesis.
7 citations
TL;DR: The synthesis of several monohydroxylated derivatives of the potent carcinogen 7H-dibenzo[c,g]carbazole (DBC), including 1-OH-DBC, 13-c-hydroxydibenzos[ c,g], and 5-hydroxy-7H- DBC, is described.
Abstract: The synthesis of several monohydroxylated derivatives of the potent carcinogen 7H-dibenzo[c,g]carbazole (DBC), including 1-hydroxy-7H-dibenzo[c,g]carbazole (1-OH-DBC), 13-c-hydroxydibenzo[c,g]carbazole (13-c-OH-DBC), and 5-hydroxy-7H-dibenzo[c,g]carbazole (5-OH-DBC), is described. 1-OH-DBC was prepared from 8-methoxy-2-tetralone and 2-naphthyl-hydrazine via Fischer indole synthesis followed by boron tribromide demethylation. The rearrangement and hydrolysis reactions to give 13-c-OH-DBC from DBC and benzoyl peroxide are discussed. The preparation and isolation of 5-OH-DBC, by hydrolysis of 5-acetoxy-N-acetyl-DBC, and the formation of its intermediate 5-acetoxy-DBC and its byproduct 6,6'-bis-(5-OH-DBC) are described in detail.
6 citations
TL;DR: In this article, the structures of these water-sensitive materials were supported by infrared, 19 F and 11 B nuclear magnetic resonance and mass spectral data, and by elemental analyses, respectively.
2 citations
TL;DR: In this article, the asymmetric Diels-Alder reaction of α,β-unsaturated aldehydes with cyclopentadiene is catalyzed by a chiral boron reagent generated in situ from BORON tribromide and a chari prolinol derivative, to afford the corresponding adducts in good yields with fairly good ees.
Abstract: The asymmetric Diels–Alder reaction of α,β-unsaturated aldehydes with cyclopentadiene is catalyzed by a novel chiral boron reagent generated in situ from boron tribromide and a chiral prolinol derivative, to afford the corresponding adducts in good yields with fairly good to excellent ees.