(Z)-3,4,4,4-Tetrachlorobut-2-enoates of Certain Natural Alcohols, Phenols, and Oximes

Previously unknown (Z)-3,4,4,4-tetrachlorobut-2-enoates 1b-20b were prepared in 77-88% yields by reaction in the presence of pyridine of 3,3,4,4,4-pentachlorobutanoic acid chloride with cetyl alcohol (1a), terpenols and terpenone oximes (2a-13a), sterols (14a and 15a), diosgenin (16a), and plant phenols and their oximes (17a-20a).     

New routes to the v-triazolo[1,5-a]pyridine and pyrazolo[1,5-a]pyridine ring systems

New routes to the v-triazolo[1,5-a]pyridine and pyrazolo[1,5-a]pyridine ring systems are described. Treatment of the N-amine salts of 2-picolinealdehyde oxime or 2-pyridyl ketone oximes with polyphosphoric acid gave v-triazolo[1,5-a]pyridines in fair yields. Treatment of 2-picolyl ketones or their oximes with O-mesitylenesulfonylhydroxylamine produced directly pyrazolo-[1,5-a]pyridines. These reactions were extended to the quinoline cases.     

Synthesis of azaheterocycles from aryl ketone O-acetyl oximes and internal alkynes by Cu-Rh bimetallic relay catalysts

A synthetic method for azaheterocycles from aryl ketone O-acetyl oximes and internal alkynes has been developed by using the Cu(OAc)(2)-[Cp*RhCl(2)](2) bimetallic catalytic system. The reactions proceeded with both of anti- and syn-isomers of oximes with a wide scope of substituents. The Cu-Rh bimetallic system could be applied for the synthesis of isoquinolines as well as β-carboline, furo[2.3-c]pyridine, pyrrolo[2,3-c]pyridine, and thieno[2,3-c]pyridine derivatives.     

Secondary ion mass spectra of quaternary pyridine aldoximes

The secondary ion mass spectra (s.i.m.s.) of the most widely used therapeutic monoquaternary pyridine aldoximes and diquaternary pyridine aldoximes, as well as some related monoquaternary ammonium salts and neutral oximes, are reported. The monoquaternary derivatives of the oximes yield prominent intact cations which provide molecular weights, and fragmentation patterns which are dominated by even-electron ions. The diquaternary oximes investigated do not give dications, but rather undergo charge separation reactions sometimes accompanied by intramolecular aromatic substitution, and they sometimes yield monoquaternaries by expulsion of a proton. The s.i. mass spectra are structure-specific for the monoquaternary salts, allowing isomer distinction in the cases examined. Quaternary salts can be quantified by s.i.m.s., and low detection limits (less than 50 ng) are demonstrated here for the oxime salts; thus s.i.m.s. is an appropriate analytical technique for the title compounds. Procedures of derivatization which convert the neutral amines to ionic compounds, such as quaternization with alkyl halides, provide a simple means of obtaining high-quality s.i.m.s.     

Beckmann rearrangement of 5-arylfurfural oximes

The acylation of 5-arylfurfural oximes with acetic anhydride in the presence of pyridine is accompanied by Beckmann rearrangement and gives 5-arylpyromucic acid acetamides. Under the same conditions, 5-arylpyromucic acid nitriles are obtained from aldoxime anti-acetates.     

Convenient preparation of O-linked polymer-bound N-substituted hydroxylamines, intermediates for synthesis of N-substituted hydroxamic acids

[reaction: see text] An efficient procedure for preparation of O-linked polymer-bound N-substituted hydroxylamines by reduction of resin-bound oximes with borane.pyridine complex in the presence of dichloroacetic acid is reported. Other reducing systems commonly used for imine or oxime reduction were ineffective, including borane.pyridine in the presence of acetic acid. Oximes derived from a variety of aromatic and aliphatic aldehydes and ketones were successfully reduced. The N-substituted products were acylated and cleaved from resin to afford N-substituted hydroxamic acids.     

<Emphasis Type="Italic">m</Emphasis>-Carborane-<Emphasis Type="Italic">C</Emphasis>-carboxylic acid esters derived from some terpene alcohols,sterols, plant phenols,and oximes of natural carbonyl compounds

Previously unknown esters were synthesized by reaction of m-carborane-C-carbonyl chloride with natural terpene alcohols, sterols, plant phenols, and oximes in the presence of pyridine.     

Pyrrole Oximes: Synthesis, Reactions, and Biological Activity. (Review)

Data on the production methods and reactions of pyrrole aldoximes and ketoximes and their derivatives are reviewed. The synthesis of new heterocycles from the pyrrole oximes is examined separately. The principal results from investigation of the biological activity of pyrrole oximes are described.     

The efficient synthesis of amphiphilic oximes of galactose and glucosamine

New amphiphilic oximes of galactose and glucosamine have been synthesized and characterized. The oxime functionality has been introduced to the first and sixth positions of a nonionic surfactant, consisting of a sugar polar head and a lipophilic side chain. The compounds are soluble in pyridine and sparingly soluble in other polar organic solvents and water.     

Furan and Thiophene Oximes: Synthesis, Reactions, and Biological Activity. (Review)

Data on methods for the production of furan and thiophene aldoximes, ketoximes, and amidoximes and their reactions are reviewed. The synthesis of new heterocycles from furan and thiophene oximes and the biological activity of derivatives of the oximes are discussed individually.     

Indole and Isatin Oximes: Synthesis, Reactions, and Biological Activity. (Review)

Data on methods for the production of isatin and indole aldoximes, ketoximes, and amidoximes and their reactions are reviewed. Individual syntheses of new heterocycles from indole and isatin oximes are discussed. The principal results from investigation of the biological activity of derivatives of the oximes are also presented.     

Copper‐Catalyzed Skeletal Rearrangements of O‐Propargylic Oximes via Cleavage of a Carbon–Oxygen Bond

In this account, we describe recent developments in copper‐catalyzed skeletal 2,3‐rearrangement reactions of O‐propargylic oximes to form four‐membered cyclic nitrones, pyridine N‐oxides, and amidodienes via N‐allenylnitrone intermediates. The sequence of events leading up to our encounter with O‐propargylic oximes is also presented.     

Esters of Vanillin and Vanillal Oximes

Vanillin and vanillal oximes 2a and 2b were used to prepare the corresponding esters 3a-k, 4a-k, and 5a-c by reaction with acyl chlorides in the presence of pyridine.     

Synthesis and unusual stability of pyridine and n‐methyl pyridinium 1,3‐dioxolanes

Differentially substituted bridged pyridinium oximes are necessary in research on antidotes for organophosphate poisoning. A solid‐phase synthesis would improve the yield and ease of purification of these compounds. To predict the lability of the linker in the final step of our proposed synthesis, we synthesized a series of pyridine and N‐methyl pyridinium acetals. These compounds proved to be resistant to acid catalyzed hydrolysis. This stability may be useful for synthetic manipulation of pyridine aldehydes.     

A novel indium-catalysed synthesis of tetra-substituted pyridine derivatives

Indium trichloride was found to be an effective catalyst for the synthesis of various tetra-substituted pyridine derivatives via Michael addition of β-dicarbonyl compounds to α,β-unsaturated oximes and subsequent ring closure.     

Quinoline Oximes: Synthesis,Reactions, and Biological Activity. (Review)

Data on the production and the reactions of quinoline aldoximes and ketoximes and their derivatives are reviewed. The synthesis of new heterocycles based on quinoline oximes is examined separately. The main results from investigation of the biological activity of quinoline oximes are presented.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 163–190, February, 2005.     

Reaction of pyridine N-oxides with Grignard reagents: a stereodefined synthesis of substituted dienal oximes

Rapid addition of Grignard reagents to pyridine N-oxides under mild conditions gave stereodefined dienal oximes in good to excellent yields. This reaction provides an efficient access to substituted olefins with defined stereochemistry that are potentially of interest as bioactives themselves or as versatile synthetic intermediates.     

Microwave-assisted syntheses of N-heterocycles using alkenone-, alkynone- and aryl-carbonyl O-phenyl oximes: formal synthesis of neocryptolepine

This research aimed to provide a new and "clean" synthetic method that would enable both known and novel N-heterocycles to be prepared efficiently. O-Phenyl oximes were found to be excellent precursors for iminyl radicals with a variety of acceptor side chains. Dihyropyrroles were made in good yields from O-phenyl oximes containing pent-4-ene acceptors. The analogous process with a hex-5-enyl acceptor did not yield a dihydropyridine, probably because the 6-exo-trig ring closure of the iminyl radical was too slow to compete with H-atom abstraction. The iminyl radical from a precursor with a pent-4-yne type side chain underwent ring closure followed by rearrangement to afford a pyrrole derivative. Suitably substituted iminyl radicals ring closed readily onto aromatic acceptors, thus enabling several polycyclic systems to be accessed. Quinolines were made from 3-phenylpropanones via their O-phenyl oximes. Syntheses of phenanthridines starting from 2-formylbiphenyls were particularly efficient, and this approach enabled the natural product trisphaeridine to be made. Starting from 2-phenylnicotinaldehyde derivatives, ring closures of the derived iminyl radicals onto the phenyl rings yielded benzo[h][1,6]naphthyridines. Similarly, ring closure onto a phenyl ring from a benzothiophene-based iminyl yielded a benzo[b]thieno[2,3-c]quinoline. By way of contrast, iminyl radical ring closure onto pyridine rings was not observed. However, iminyl radicals did cyclize onto indoles, enabling indolopyridines to be prepared. The latter route was exploited in a short formal synthesis of neocryptolepine starting from 2-((1H-indol-3-yl)methyl)cyclohexanone.     

2-Bromo-3,4,4-trichlorobut-3-enoates of certain natural alcohols, phenols, and oximes of carbonyl compounds

Previously undescribed 2-bromo-3,4,4-trichlorobut-3-enoates 1b-23b were synthesized in 84–91% yield from natural alcohols including terpenes and steroids, plant phenols, and oximes of natural carbonyl compounds 1a-23a by reaction of 2-bromo-3,4,4-trichlorobut-3-enoyl chloride in the presence of pyridine. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 212–215, May–June, 2006.     

Oximes of five-membered heterocyclic compounds with three and four heteroatoms 2. Synthesis of derivatives,reactions, and biological activity (Review)

Data on the reactions of triazole, tetrazole, dioxazole, oxadiazole, and thiadiazole aldoximes, ketoximes, and amidoximes, their synthesis, and the reactions of their derivatives are reviewed. The synthesis of new heterocycles based on the oximes of five-membered heterocyclic compounds with three and four heteroatoms is examined separately. The principal results from investigation of the biological activity of ethers of these oximes are also presented. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 963–990, July, 2008.