107616-26-2Relevant academic research and scientific papers
Dihydrobenzoxazines and Tetrahydroquinoxalines by a Tandem Reduction-Reductive Amination Reaction
Bunce, Richard A.,Herron, Derrick M.,Hale, Lu Y.
, p. 1031 - 1039 (2007/10/03)
A tandem reduction-reductive amination reaction has been applied to the synthesis of 3,4-dihydro-2H-1,4-benzoxazines and 1-acetyl-1,2,3,4-tetrahydroquinoxalines. The nitroketones required for the benzoxazine ring closures were prepared by (A) alkylation of the anion derived from 2-nitrophenol with an allylic halide or (B) nucleophilic aromatic substitution of an allylic alkoxide on 2-fluoro-1-nitrobenzene followed by ozonolysis. Precursors for the quinoxalines were prepared by alkylation of the anion of 2-nitroacetanilide with an allylic halide followed by ozonolysis. Catalytic hydrogenation of the nitroketones using 5% palladium-on-carbon in methanol then gave the target heterocycles by a reduction-reductive amination sequence. The N-methyl derivatives for both ring systems were easily prepared by adding 5-10 equivalents of aqueous formaldehyde prior to the reduction. The dihydrobenzoxazines were isolated in high yield following purification by chromatographic methods; tetrahydroquinoxalines were isolated in a similar manner and possessed differentiated functionality on the two nitrogens.
Iododediazoniation of Arenediazonium Salts Accompanied by Aryl Radical Ring Closure
Beckwith, Athelstan L. J.,Meijs, Gordon F.
, p. 1922 - 1930 (2007/10/02)
Treatment of o-(allyloxy)benzenediazonium tetrafluoroborate (1a) with sodium iodide in acetone affords the cyclized iodide 2a in good yield by a mechanism involving the generation and exo cyclization of the aryl radical 6a.Other diazonium salts (1b-i) containing suitable unsaturated side chains behave similarly, but those (1l,1m) in which there is an N-allylsulfonamido group yield mainly products formed by endo cyclization.The diazonium salts 1j and 1k do not give cyclized products.Factors affecting the mechanism, rates, and regiochemistry of the reaction are discussed.
