Reactions of vinyl chloroformate and oxime chloroformates with silver salts

Beak, Peter; Barron, James A.

doi:10.1021/jo00956a007

Cited by 6 publications

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“…The Schmidt reaction of ketones was first reported over fifty years ago and the scope and mechanism of this rearrangement reaction have been extensively reviewed by Smith (1) and, more recently, by Koldobskii et al (2) Interest in this reaction, and the mechanistically related Beckmann rearrangement, remains high, however, as indicated by a number of recent publications (3)(4)(5)(6). Some years ago, Evans and Lockhart (7) had studied a series of tetralones l a and contrasted their behavior in the Schmidt reaction with that of the analogous chromanones 16.…”

Section: Introductionmentioning

confidence: 99%

The Behavior of Thiochromanone and Isothiochromanone Sulfoxides in the Schmidt Reaction: Isolation of a Novel Azide Product from Thiochromone Sulfone

Still¹,

Thomas²,

Clish³

1975

Can. J. Chem.

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. Can. J . Chem. 53,276(1975).The Schmidt reaction has been carried out on thiochroman-4-one 1-oxide and a number of related sulfoxides. In all cases lactam formation by attack of HN3 on the carbonyl group of the keto sulfoxide appears to predominate, with no evidence for sulfoximine formation. The question of aryl vs. alkyl migration, as in other systems, is dependent on the degree of substitution of the alkyl group. When the Schmidt reaction was carried out upon thiochromone 1,l-dioxide two products, the lactam resulting from preferential vinyl migration and a novel a-azido sulfone resulting from 1,4-addition, were obtained. On a effectue la reaction de Schmidt sur la thiochromanone-4 oxyde-1 et un certainnombre de sulfoxydes qui lui sont apparent&. Dans tous les cas, il y a formation de lactame par attaque de HN3 sur le groupement carbonyle du cCto-sulfoxyde et cette riaction semble predominante; on n'a trouve aucune preuve expirimentale pour la formation d'une sulfoxymine. La question de la migration des groupes aryles par opposition a la migration a des groupes alkyles depend d u degre de substitution en accord avec ce qui a CtC observe dans d'autres systkmes. Lorsque I'on effectue la rtaction de Schmidt sur la thiochromonedioxyde-1

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Section: Introductionmentioning

confidence: 99%

The Behavior of Thiochromanone and Isothiochromanone Sulfoxides in the Schmidt Reaction: Isolation of a Novel Azide Product from Thiochromone Sulfone

Still¹,

Thomas²,

Clish³

1975

Can. J. Chem.

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“…22 9-Fluorenone-oxime-chloroformate (17). 30,31 9-Fluorenone-oxime (1.95 g, 0.01mol) was suspended in 200 mL of tetrachloromethane. A solution of phosgene in toluene (25 mL, c ) 2 mol L -1 , 0.05 mol) was added dropwise at -7 °C.…”

Section: Methodsmentioning

confidence: 99%

Generation and Characterization of the Selenocysteinyl Radical: Direct Evidence from Time-Resolved UV/Vis, Electron Paramagnetic Resonance, and Fourier Transform Infrared Spectroscopy

et al. 2005

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The selenocysteinyl radical 1 has been generated for the first time by laser flash photolysis (lambda(exc) = 266 nm) of dimethyl bis(N-tert-butoxycarbonyl)-l-selenocystine 2 and of [(9-fluorenylideneamino)oxycarbonyl]methyl(N-tert-butoxycarbonyl)-l-selenocysteine 3 in acetonitrile and characterized by time-resolved (TR) UV/Vis, Fourier transform infrared (FTIR), and electron paramagnetic spectroscopy in combination with theoretical methods. A detailed product study was conducted using gas chromatography and one- and two-dimensional NMR spectroscopy. In the case of [(9-fluorenylideneamino)oxycarbonyl]methyl(N-tert-butoxycarbonyl)-l-selenocysteine 3, the (9-fluorenylideneamino)oxycarbonyl moiety serves as a photolabile protection group providing a "caged selenocysteinyl radical" suitable for biophysical applications. Cleavage of the diselenide bridge or the selenium-carbonyl bond by irradiation is possible in high quantum yields. Because of the lack of a good IR chromophore in the mid-IR region, the selenocysteinyl radical 1 cannot be monitored directly by TR FTIR spectroscopy. TR UV/Vis spectroscopy revealed the formation of the selenocysteinyl radical 1 from both precursors. The selenocysteinyl radical 1 has a lifetime tau approximately 63 mus and exhibits a strong band located at lambda(max) = 335 nm. Calculated UV absorptions of the selenocysteinyl radical (UB3LYP/6-311G(d,p)) are in good agreement with the experimental results. The use of TR UV/Vis spectroscopy permitted the determination of the decay rates of the selenocysteinyl radical in the presence of two quenchers. The product studies demonstrated the reversible photoreaction of dimethyl bis(N-tert-butoxycarbonyl)-l-selenocystine 2. Products of the photolysis of the "caged selenocysteinyl radical" precursor 3 are dimethyl bis(N-tert-butoxycarbonyl)-l-selenocystine 2, carbon dioxide, and some further smaller fragments. In addition, the photodecomposition of the (9-fluorenylideneamino)oxycarbonyl moiety produced 9-fluorenone-oxime 4, 9-fluoren-imine 5, and 6 and 7 as products of the dimerization of two 9-fluorenoneiminoxy radicals 8.

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TheBeckmann Reactions: Rearrangements, Elimination–Additions, Fragmentations, and Rearrangement–Cyclizations

Gawley

1988

Organic Reactions

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The Beckmann rearrangement, the acid‐mediated isomerization of oximes to amides, was discovered by Beckmann in 1886. As one of the oldest and most familiar transformations in organic chemistry, it has been reviewed several times. What has become known as the Beckmann fragmentation was in fact first observed by Wallach in 1889 but was not developed extensively until the 1960s. It has been referred to by several names over the years and has also been reviewed. The rearrangement cyclization is the intramolecular cyclization of a nitrilium ion generated by Beckmann rearrangement from an oxime. Within the context of an aromatic terminator, the process was first reported by Goldschmidt in 1895. Wallach reported the first case of an aliphatic terminator in 1901, although the reported structure was incorrect, and Perkin was apparently the first to observe a heteroatom terminator, but he also reported an incorrect structure. The process has been exploited only quite recently. This chapter is an update of these reactions, last reviewed in this series in 1960. Not covered are transformations that have been labeled Beckmann‐type reactions but are mechanistically unrelated. The most prominent of these is the so‐called photochemical Beckmann rearrangement, first observed by De Mayo in 1963 and discussed in a review several years ago. Worthy of mention, however, is the fact that many oximes that suffer fragmentation under acidic conditions undergo rearrangement when photolyzed. Throughout this chapter, the ( E ) and ( Z ) nomenclature is used to describe oxime geometry.

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Reactions of vinyl chloroformate and oxime chloroformates with silver salts

Cited by 6 publications

References 0 publications

The Behavior of Thiochromanone and Isothiochromanone Sulfoxides in the Schmidt Reaction: Isolation of a Novel Azide Product from Thiochromone Sulfone

The Behavior of Thiochromanone and Isothiochromanone Sulfoxides in the Schmidt Reaction: Isolation of a Novel Azide Product from Thiochromone Sulfone

Generation and Characterization of the Selenocysteinyl Radical: Direct Evidence from Time-Resolved UV/Vis, Electron Paramagnetic Resonance, and Fourier Transform Infrared Spectroscopy

TheBeckmann Reactions: Rearrangements, Elimination–Additions, Fragmentations, and Rearrangement–Cyclizations

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