A Convenient Synthesis of 2,4-Dihydroxy-2<i>H</i>-1,4-benzoxazin-3(4<i>H</i>)-one

“…This may be a result of the two basic centres now available for the formation of diastereomeric complexes which are conformationally more rigid than those formed by the phenylethylamine enantiomer. Table 1 shows that all racemic methyl acetals, 3, 4 and 9, having hydroxamic acid units, and also 5, 6 and 10 having lactam units, can be discriminated into enantiomers using (-)-quinine as CSA in CD,C12 .…”

Section: Influence Of Structures Of Enantiomers and Various Csa On Thmentioning

confidence: 99%

First discrimination of enantiomeric cyclic hemiacetals and methyl acetals derived from hydroxamic acids and lactams of Gramineae by means of ¹H NMR using various chiral solvating agents

Klein

Hartenstein

Sicker

1994

Magnetic Reson in Chemistry

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The discrimination of enantiomeric cyclic hemiacetals and methyl acetals derived from hydroxamic acids and lactams with the 2H-1,4-benzoxazin-3(4H)-one and 2H-1,4-benzothiazin-3(4H)sne skeleton was investigated using Conditions for the enantiomeric discrimination of six configurationally stable methyl acetals are reported. 2,4-Dihydroxy-2H-1,4-benzoxazin-3(4~-one and its 7-methoxy derivative, bioactive aglucones from Gramineae species, are the first cyclic hemiacetals that could be differentiated into enantiomem by means of 'H NMR, despite their oxo-cyclo tautomerization that prevented enantioseparation by chromatography or capillary electrophoresis. However, 2-hydroxy-2H-1,4-benzothiazin-3(4~-ones (thiohemiacetals) could not be differentiated by the use of these CSA. The influence of the structure of the enantiomers, CSA, temperature and concentration on the size of the chemical shift anisochrony is discussed.

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“…A variety of methods to achieve this transformation have been reported, including those using stoichiometric zinc or tin 4 as well as palladium 5 or platinum 6 catalyzed partial reduction. Many of these methods can be somewhat problematic.…”

mentioning

confidence: 99%

“…However, treatment of the unpurified reaction mixture with Boc 2 O and Et 3 N resulted in the formation of a protected hydroxamic acid that could be easily be purified by standard chromatographic methods. 4c …”

mentioning

confidence: 99%

Reductive Cyclizations of Nitroarenes to Hydroxamic Acids by Visible Light Photoredox Catalysis

Cismesia¹,

Ischay²

2013

Synthesis

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We have developed a photocatalytic reduction of nitroarenes as an efficient, chemoselective route to biologically important N-phenyl hydroxamic acid scaffolds. Optimal conditions call for 2.5 mol% of a ruthenium photocatalyst, visible light irradiation, and a dihydropyridine terminal reductant. Because of the mild nature of the visible light activation, functional groups that might be sensitive to other non-photochemical reduction methods are easily tolerated.

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A Convenient Synthesis of 2,4-Dihydroxy-2H-1,4-benzoxazin-3(4H)-one

Cited by 44 publications

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Cyclic hydroxamic acid inhibitors of prostate cancer cell growth: Selectivity and structure activity relationships

Cyclic hydroxamic acid inhibitors of prostate cancer cell growth: Selectivity and structure activity relationships

First discrimination of enantiomeric cyclic hemiacetals and methyl acetals derived from hydroxamic acids and lactams of Gramineae by means of ¹H NMR using various chiral solvating agents

Reductive Cyclizations of Nitroarenes to Hydroxamic Acids by Visible Light Photoredox Catalysis

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A Convenient Synthesis of 2,4-Dihydroxy-2H-1,4-benzoxazin-3(4H)-one

Cited by 44 publications

References 0 publications

Cyclic hydroxamic acid inhibitors of prostate cancer cell growth: Selectivity and structure activity relationships

Cyclic hydroxamic acid inhibitors of prostate cancer cell growth: Selectivity and structure activity relationships

First discrimination of enantiomeric cyclic hemiacetals and methyl acetals derived from hydroxamic acids and lactams of Gramineae by means of 1H NMR using various chiral solvating agents

Reductive Cyclizations of Nitroarenes to Hydroxamic Acids by Visible Light Photoredox Catalysis

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First discrimination of enantiomeric cyclic hemiacetals and methyl acetals derived from hydroxamic acids and lactams of Gramineae by means of ¹H NMR using various chiral solvating agents