Cyclobutanes in organic synthesis. Part I. Fragmentation to 1,4-dicarbonyl compounds. General considerations

1970 ◽  
Vol 48 (9) ◽  
pp. 1436-1445 ◽  
Author(s):  
N. R. Hunter ◽  
G. A. MacAlpine ◽  
H. J. Liu ◽  
Z. Valenta
Keyword(s):  
Carbonyl Group ◽  
Organic Synthesis ◽  
Alkyl Group ◽  
Acetate Group ◽  
Dicarbonyl Compounds ◽  
Group A ◽  
Hydrolysis Of

Photo-cycloaddition of vinyl acetates to 2-cyclohexenones followed by hydrolysis of the acetate group and by oxidative fragmentation leads to 2-alkyl-2-cyclohexenones in which the newly introduced alkyl group bears a 2′-carbonyl group. A similar, less generally applicable method, involving photo-cycloaddition, bromination, and heterolytic fragmentation is also described. Possible applications of this sequence in organic synthesis are discussed.

STUDIES ON REACTIONS RELATING TO CARBOHYDRATES AND POLYSACCHARIDES. XXXIV. THE CONSTITUTION OF LEVAN AND ITS RELATION TO INULIN

1931 ◽  
Vol 4 (3) ◽  
pp. 221-239 ◽  
Author(s):  
Harold Hibbert ◽  
R. Stuart Tipson ◽  
F. Brauns
Keyword(s):  
Carbonyl Group ◽  
Methyl Alcohol ◽  
Hydroxyl Groups ◽  
Complete Hydrolysis ◽  
Subsequent Hydrolysis ◽  
Group A ◽  
And Behavior ◽  
Hydrolysis Of

A description is given of the properties of levan, a polysaccharide obtained by the action of Bacillus mesentericus, and of its enzyme, on sucrose; in particular, its complete hydrolysis to fructose, and behavior when subjected to acetylation and methylation.By hydrolysis of trimethyl levan, a crystalline trimethyl fructose was obtained (the first crystalline methylated γ-sugar to be synthesized). This yielded a trimethyl methylfructoside on condensation with methyl alcohol containing HCl. The properties of these compounds are described for the first time.On methylation and subsequent hydrolysis of the glucide, a tetramethyl fructose was obtained having properties identical with those of the tetramethyl fructose obtained by hydrolysis of heptamethyl sucrose.Oxidation of the new trimethyl fructose yielded a dibasic dimethyl lactol acid, and esterification of the latter, followed by methylation and treatment with dry ammonia, gave a crystalline diamide. These results show that the new crystalline trimethyl fructose is 1:3:4-trimethyl fructofuranose.It follows from this that levan is a polymerized anhydro-fructofuranose with linkages at positions 2 and 6 of the fructose chain, thus differing from inulin which has been shown to be an anhydro-fructofuranose with linkages at positions 1 and 2.The synthesis of levan thus represents a further example of the polymerization of an anhydro sugar taking place through the medium of the γδ hydroxyl groups. It serves to emphasize the importance of these spatial positions with reference to the carbonyl group, a phenomenon to which attention has been drawn repeatedly by Hibbert.

DFT study on the hydrolysis of metsulfuron-methyl: A sulfonylurea herbicide

2018 ◽  
Vol 17 (08) ◽  
pp. 1850050 ◽  
Author(s):  
Qiuhan Luo ◽  
Gang Li ◽  
Junping Xiao ◽  
Chunhui Yin ◽  
Yahui He ◽  
...  
Keyword(s):  
Free Energy ◽  
Water Molecule ◽  
Carbonyl Group ◽  
Energy Barrier ◽  
Density Functional ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Metsulfuron Methyl ◽  
Catalytic Role ◽  
Hydrolysis Of

Sulfonylureas are an important group of herbicides widely used for a range of weeds and grasses control particularly in cereals. However, some of them tend to persist for years in environments. Hydrolysis is the primary pathway for their degradation. To understand the hydrolysis behavior of sulfonylurea herbicides, the hydrolysis mechanism of metsulfuron-methyl, a typical sulfonylurea, was investigated using density functional theory (DFT) at the B3LYP/6-31[Formula: see text]G(d,p) level. The hydrolysis of metsulfuron-methyl resembles nucleophilic substitution by a water molecule attacking the carbonyl group from aryl side (pathway a) or from heterocycle side (pathway b). In the direct hydrolysis, the carbonyl group is directly attacked by one water molecule to form benzene sulfonamide or heterocyclic amine; the free energy barrier is about 52–58[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. In the autocatalytic hydrolysis, with the second water molecule acting as a catalyst, the free energy barrier, which is about 43–45[Formula: see text]kcal[Formula: see text]mol[Formula: see text], is remarkably reduced by about 11[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. It is obvious that water molecules play a significant catalytic role during the hydrolysis of sulfonylureas.

scholarly journals MW irradiation and ionic liquids as green tools in hydrolyses and alcoholyses

2020 ◽  
Vol 10 (1) ◽  
pp. 001-010 ◽  
Author(s):  
Nikoletta Harsági ◽  
Betti Szőllősi ◽  
Nóra Zsuzsa Kiss ◽  
György Keglevich
Keyword(s):  
Ionic Liquids ◽  
Alkaline Hydrolysis ◽  
Alkyl Group ◽  
Phosphinic Acid ◽  
Reaction Times ◽  
Alternative Possibility ◽  
First Order ◽  
Pseudo First Order ◽  
Mw Irradiation ◽  
Hydrolysis Of

Abstract The optimized HCl-catalyzed hydrolysis of alkyl diphenylphosphinates is described. The reaction times and pseudo-first-order rate constants suggested the iPr > Me > Et ∼ Pr ∼ Bu order of reactivity in respect of the alkyl group of the phosphinates. The MW-assisted p-toluenesulfonic acid (PTSA)-catalyzed variation means a better alternative possibility due to the shorter reaction times, and the alkaline hydrolysis is another option. The transesterification of alkyl diphenylphosphinates took place only in the presence of suitable ionic liquids, such as butyl-methylimidazolium hexafluorophosphorate ([bmim][PF6]) and butyl-methylimidazolium tetrafluoroborate ([bmim][BF4]). The application of ethyl-methylimidazolium hydrosulfate ([emim][HSO4]) and butyl-methylimidazolium chloride ([bmim][Cl]) was not too efficient, as the formation of the ester was accompanied by the fission of the O–C bond resulting in the formation of Ph2P(O)OH. This surprising transformation may be utilized in the phosphinate → phosphinic acid conversion.

scholarly journals Use of a Hydrolytic Procedure and Spectrometric Methods in the Structure Elucidation of a Thiocarbonyl Analogue of Sildenafil Detected as an Adulterant in an Over-the-Counter Herbal Aphrodisiac

2009 ◽  
Vol 92 (5) ◽  
pp. 1336-1342 ◽  
Author(s):  
John C Reepmeyer ◽  
D Andr d'Avignon
Keyword(s):  
Dietary Supplement ◽  
Carbonyl Group ◽  
Minor Component ◽  
Pyrimidine Ring ◽  
Over The Counter ◽  
Methyl Group ◽  
Nmr Spectrometry ◽  
A Minor ◽  
Hydrolysis Of ◽  
Hydroxyethyl Group

Abstract A sildenafil-related compound was detected in an herbal dietary supplement marketed as an aphrodisiac. The compound was identified as an analogue of sildenafil in which the carbonyl group in the pyrimidine ring of sildenafil was substituted with a thiocarbonyl group, and the methyl group on the piperazine ring was substituted with a hydroxyethyl group. Based on this structure, the compound was named thiohydroxyhomosildenafil. The structure of the compound was established using HPLC/MS, UV spectrometry, electrospray ionization-MS/MS, NMR spectrometry, and a hydrolytic process. One key product of hydrolysis was 1-(2-hydroxyethyl)-piperazine; the identification of this product defined the amine portion of the compound. Another key product of hydrolysis was hydroxyhomosildenafil, generated by hydrolysis of the thiocarbonyl group to a carbonyl group (C S C O). Hydroxyhomosildenafil was detected as a minor component in the dietary supplement.

scholarly journals Photocatalytic Atom Transfer Radical Addition to Olefins Utilizing Novel Photocatalysts

Molecules ◽  
2019 ◽  
Vol 24 (9) ◽  
pp. 1644 ◽  
Author(s):  
Errika Voutyritsa ◽  
Ierasia Triandafillidi ◽  
Nikolaos V. Tzouras ◽  
Nikolaos F. Nikitas ◽  
Eleftherios K. Pefkianakis ◽  
...  
Keyword(s):  
Metal Complexes ◽  
Organic Synthesis ◽  
Alkyl Group ◽  
Radical Addition ◽  
Bidentate Ligand ◽  
Atom Transfer ◽  
Broad Scope ◽  
Atom Transfer Radical Addition ◽  
Terpyridine Ligands ◽  
Photocatalytic Reactions

Photocatalysis is a rapidly evolving area of research in modern organic synthesis. Among the traditional photocatalysts, metal-complexes based on ruthenium or iridium are the most common. Herein, we present the synthesis of two photoactive, ruthenium-based complexes bearing pyridine-quinoline or terpyridine ligands with extended aromatic conjugation. Our complexes were utilized in the atom transfer radical addition (ATRA) of haloalkanes to olefins, using bromoacetonitrile or bromotrichloromethane as the source of the alkyl group. The tailor-made ruthenium-based catalyst bearing the pyridine-quinoline bidentate ligand proved to be the best-performing photocatalyst, among a range of metal complexes and organocatalysts, efficiently catalyzing both reactions. These photocatalytic atom transfer protocols can be expanded into a broad scope of olefins. In both protocols, the photocatalytic reactions led to products in good to excellent isolated yields.

Hydration of the Carbonyl Group. A Theoretical Study of the Cooperative Mechanism

1995 ◽  
Vol 117 (15) ◽  
pp. 4240-4260 ◽  
Author(s):  
Saul Wolfe ◽  
Chan-Kyung Kim ◽  
Kiyull Yang ◽  
Noham Weinberg ◽  
Zheng Shi
Keyword(s):  
Carbonyl Group ◽  
Theoretical Study ◽  
Group A
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