Approaches to α-amino acids via rearrangement to electron-deficient nitrogen: Beckmann and Hofmann rearrangements of appropriate carboxyl-protected substrates

• Sosale Chandrasekhar and
• V. Mohana Rao

Beilstein J. Org. Chem. 2012, 8, 1393–1399, doi:10.3762/bjoc.8.161

• Sosale Chandrasekhar V. Mohana Rao Department of Organic Chemistry, Indian Institute of Science, Bangalore 560 012, India 10.3762/bjoc.8.161 Abstract The titled approaches were effected with various 2-substituted benzoylacetic acid oximes 3 (Beckmann) and 2-substituted malonamic acids 9 (Hofmann

• complicated by competing deacylation, hydroxamic acid formation, etc. We are only aware of two reports [8][9] of the Beckmann rearrangement of β-keto ester oximes. A particular problem was the formation of isoxazolone byproducts, which apparently limited the synthesis to α,α-disubstituted derivatives

• preparation of 1 is also presented herein). Ketone 1 was α-alkylated in high yields to various 2 via sodium hydride deprotonation and reaction of the resulting enolate with a variety of alkyl bromides or iodides. Alkyl derivatives 2 may be converted conventionally to the corresponding oximes 3. The Beckmann

Screening of ligands for the Ullmann synthesis of electron-rich diaryl ethers

• Nicola Otto and
• Till Opatz

Beilstein J. Org. Chem. 2012, 8, 1105–1111, doi:10.3762/bjoc.8.122

• , phosphinites, phosphonates, imines, diimines, oximes, oxime ethers and diketones were selected for the screening (Figure 2). Several of these compounds have been employed in diaryl ether syntheses before [22][23][24]. As a starting point, N,N-dimethylglycine (L1) introduced by Ma et al. [22][25] in combination

• screening, as can be seen by comparison of L28, L32, and L33. Furthermore, oxime ethers, which, to the best of our knowledge, represent a new class of ligands for Ullmann-type couplings, were also screened in the model reaction. All tested oxime ethers and oximes showed catalytic activity, although the

• substrate conversion was lower compared to the amino acid-derived ligands. The catalytic activities of the oximes did not, however, differ from those of the oxime ethers. On the other hand, the salicyl aldehyde-derived oxime ether and oxime ligands [31] showed only poor substrate conversions in comparison

Highly efficient cyclosarin degradation mediated by a β-cyclodextrin derivative containing an oxime-derived substituent

• Michael Zengerle,
• Florian Brandhuber,
• Christian Schneider,
• Franz Worek,
• Georg Reiter and
• Stefan Kubik

Beilstein J. Org. Chem. 2011, 7, 1543–1554, doi:10.3762/bjoc.7.182

• substituents represents a promising approach for the development of scavengers able to detoxify highly toxic nerve agents. Keywords: acetylcholinesterase; cyclodextrins; cyclosarin; neurotoxic organophosphonates; oximes; Introduction Cyclodextrins, cyclic oligosaccharides composed of α-1,4-linked D-glucose

• reactive unit and allowing it to mediate another reaction. Here, we describe our first results in this project, involving a series of β-cyclodextrin derivatives with substituents on the primary face of the cyclodextrin ring, containing oximes as nucleophilic groups. Oximes are well-known antidotes for the

• treatment of OP poisonings. Their mode of action involves reactivation of the OP-inhibited acetylcholinesterase [29], yet previous work has also indicated that certain oximes are able to cleave OPs directly [30]. We show that some of our cyclodextrin derivatives efficiently reduce GF concentrations in

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• Imines and oximes are versatile synthetic intermediates for the preparation of dyes, pharmaceuticals, and agricultural chemicals. Sun et al. have reported a multi-task Au/hydroxyapatite reagent for the heterogeneous catalyzed oxidation of alcohols and amines to imines or oximes [56]. N-alkylation of

• . In addition to intermolecular addition, Mukherjee and Widenhoefer recently reported a gold(I)-catalyzed intramolecular amination of allylic alcohols 130 with alkylamines (Scheme 23) [61]. 3.2 Imines as nucleophiles Gold-catalyzed cyclizations of O-propioloyl oximes via C–N bond formation followed by

Novel base catalysed rearrangement of sultone oximes to 1,2-benzisoxazole- 3-methane sulfonate derivatives

• Veera Reddy Arava,
• Udaya Bhaskara Rao Siripalli,
• Vaishali Nadkarni and
• Rajendiran Chinnapillai

Beilstein J. Org. Chem. 2007, 3, No. 20, doi:10.1186/1860-5397-3-20

• -3-methanesulfonates and 4-oximino-2,3-dihydrobenzoxathiin-2,2-dioxides (sultone oximes) is described. These compounds are important intermediates for the preparation of zonisamide, an anti-convulsant drug. Background 3-Alkyl-1,2-benzisoxazole derivatives are known to have important biological

• was developed by Dianippon of Japan. Compounds 1 were originally prepared from the rearrangement of coumarin-4-one oximes 3 as shown in Scheme 1. The 1,2-benzisoxazole-3-acetic acids were converted into halogenated compounds, then reacted with various different nucleophiles to generate the compounds 1

• ) failed to produce the cyclised products and gave only salicylic acid derivatives. All the 1,2-benzoxathiin-4(3H)-one-2,2-dioxides 6 were characterised from their analytical and spectral data. Conversion of ketones 6 into the corresponding oximes 5 proceeded uneventfully, and oximes 5 were characterised