- Synthesis of 1,11,11-trimethyl-3,6-diazotricyclo [6.2.1.0 2,7]undeca-2,6-diene and 1,15,15-trimethyl-3,10-diazotetracyclo[10.2. 1.02,11.04,9]pentadeca-2,4(9),5,7,10-pentaene from camphoroquinone enantiomers
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Optically active camphordihydro-2,3-pyrazine and camphorquinoxaline were prepared from camphoroquinone enantiomers. It was shown that (1S,4R)-(+)-camphoroquinone was formed by oxidation of (1S,3R, 4R)-(-)-3-bromocamphor and (1R,4S)-(-)-camphoroquinone from (1R,3S, 4S)-(+)-3-bromocamphor, respectively. Camphor anhydride was a side product (6-10%) of the reaction. Springer Science+Business Media, Inc. 2007.
- Adamenko,Frolova,Panteleeva,Kuchin
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- An improved synthesis of camphorquinone-3-oxime
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Camphorquinone 3-oxime is prepared in 77% yield in one step from camphor. The synthesis avoids the use of toxic selenium reagents, and provides the syn compound as the major stereoisomer.
- Love, Brian E.,Jones, Edward G.
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- Synthesis of terpene diamines based on camphor-derived dinitriles
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Diamines are useful as additional ligands in enantioselective hydrogenations. A new route for synthesizing such a rigid diamine from naturally available camphor via camphor oxime/camphor furoxan/deoxygenation in large scale was developed. The resulting dinitriles were subjected to hydrogenation with Raney Ni or other heterogenous catalysts. In most cases, the reduction resulted in complex mixtures. The best results were obtained with Raney Ni in THF/H2O in strongly basic media (NaOH), which affords compound 5b only in good yield. Homogenous catalyst like Grubbs 2nd generation reduced only the less hindered CN group to yield an amino nitrile.
- Kinzl, Florian R.,Riepl, Herbert M.
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- The Role of Side-Arms for Supramolecular Affinity Materials Based on 9,9′-Spirobifluorenes
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An eightfold functionalized D2d-symmetric 9,9′-spirobifluorene was condensed with a collection of diketones with elaborated structural features to form three-dimensional supramolecular architectures with active surfaces. Gas-sorption measuremen
- Pyka, Isabella,Nikl, Joachim,Schollmeyer, Dieter,Waldvogel, Siegfried R.
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- Enantioselective Addition of Diethylzinc to Aldehydes Catalyzed by Chiral O,N,O-tridentate Phenol Ligands Derived from Camphor
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Chiral O,N,O-tridentate phenol ligands bearing a camphor backbone were found to be effective chiral catalysts for the enantioselective addition of diethylzinc to aromatic aldehydes, resulting in high enantioselectivities (80-95% ee) at room temperature.
- Lee, Dong-Sheng,Chang, Shu-Ming,Ho, Chun-Ying,Lu, Ta-Jung
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- Synthesis and evaluation of camphor and cytisine-based cyanopyrrolidines as DPP-IV inhibitors for the treatment of type 2 diabetes mellitus
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In this study, bornyl- and cytisine-based cyanopyrrolidines as potent dipeptidyl peptidase-IV (DPP-IV) inhibitors were synthesised. The in vitro inhibiting activities of bornyl- and cytisine derivatives towards DPP-IV were evaluated. Bornyl-based cyanopyrrolidines were shown to have moderate inhibitory activity with regard to DPP-IV (1.27–15.78 μM). A docking study was performed to elucidate the structure-activity relationship of the obtained compounds. The in vivo hypoglycemic activities of the same compounds were evaluated with the oral glucose tolerance test (OGTT) in mice. Bornyl-based cyanopyrrolidines were shown to have good hypoglycemic activity.
- Kuranov,Tsypysheva,Khvostov,Zainullina, Liana F.,Borisevich,Vakhitova, Yu.V.,Luzina,Salakhutdinov
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- An environment friendly preparation of 3-bromocamphor and camphorquinone
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The bromination of camphor has been carried out on a multi-gram scale by a mixture of KBr and KBrO3 in the presence of acid or with HBr/NaBr - H+ and H2O2/oxone as the oxidant. The 3-bromocamphor is then efficiently converted to camphorquinone by an improved oxidation protocol using DMSO and sodium carbonate of tetrabutyl ammonium iodide.
- Kannappan, Jayaraman,Bedekar, Ashutosh V.
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- Stereoselective cyclopalladation of 2,3-camphorquinone 3-diphenylmethylimine
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A reaction of (1R,4 S)-3-diphenylmethylimino-1,7,7-trimethylbicyclo[2.2.1]heptan-2-one with lithium tetrachloropalladate gives a palladium(II) complex with a monodentately coordinated ligand, whereas chiral palladacyclic compounds are formed in the case o
- Gur'Eva,Zalevskaya,Alekseev,Frolova,Slepukhin,Kuchin
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- Efficient synthesis of camphorquinone from camphor
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In this study, we discussed an efficient approach for the synthesis of camphorquinone from camphor by the continuous reaction of bromination and oxidation. The oxidation of 3-bromocamphor was catalyzed by Fe-porphyrins with air. The catalytic activity of iron-metallated functional porphyrins was investigated under optimization conditions. The results showed that this method was a milder alternative to the reported methods, with a simple, greener procedure in which the advantages were the utilization of air as the oxidant and the use of metalloporphyrins as catalysts. Copyright Taylor & Francis Group, LLC.
- Wang, Jian,Li, Peng,Ni, Chengliang,Yan, Hong,Zhong, Rugang
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- (+)-Camphor and (?)-borneol derivatives as potential anti-orthopoxvirus agents
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Although the World Health Organisation had announced that smallpox was eradicated over 40 years ago, the disease and other related pathogenic poxviruses such as monkeypox remain potential bioterrorist weapons and could also re-emerge as natural infections
- Sokolova, Anastasiya S.,Kovaleva, Kseniya S.,Yarovaya, Olga I.,Bormotov, Nikolay I.,Shishkina, Larisa N.,Serova, Olga A.,Sergeev, Alexander A.,Agafonov, Alexander P.,Maksuytov, Rinat A.,Salakhutdinov, Nariman F.
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- A novel and efficient synthesis of camphorquinone from camphoric acid
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Camphorquinone (1), an important fine chemical and medicinal product derived from camphor, was efficiently synthesized from easily available camphoric acid (2). The key steps include acyloin condensation using Me 3SiCl as a scavenger of alkoxides and oxidation of the bis(trimethylsilyl) derivative 4 by bromine in CCl4. The new method offers an efficient alternative synthesis of camphorquinone (1).
- Tan, Qitao,Wang, Yunying,Li, Daliang,Wen, Jiwu,You, Tianpa
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Read Online
- Novel synthetic method of camphorquinone
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The invention relates to a novel synthetic method of camphorquinone, which is a method for preparing camphorquinone from camphor in the presence of a catalyst. The invention further provides a methodfor preparing camphorquinone, which can effectively reduce the toxicity of the used catalyst and reflect the harm to the environment, and ensures a high yield of the reaction while simplifying the process flow. According to the method, clean energy microwave irradiation instead of conventional energy is utilized, so that the pollution of the reaction to the environment is greatly reduced while thereaction yield is ensured, and the purpose of green chemistry is met.
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Paragraph 0018-0019
(2020/05/30)
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- Selectively polymerizable compositions and methods of use in vivo
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Otologic materials and methods are provided. For example, a cell-adhesive, biodegradable hydrogel scaffold loaded with time-released drugs for repairing chronic tympanic membrane perforations is disclosed, methods of making same and administering same are provided. This hydrogel may promote vascular in-growth and epithelial cell growth of the tympanic membrane with the purpose of closing the perforation and providing a barrier between the external and middle ear. The hydrogel is initially a liquid polymer that only gels upon exposure to specific conditions, such as exposure to light. This scaffold may simultaneously induce repair of the tympanic membrane while preventing or alleviating middle ear infection, thus filling a void in current tympanic membrane perforation therapies.
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- Method for producing camphorquinone by taking byproduct generated in camphor synthesis process as raw material
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The invention provides a method for producing camphorquinone by taking a byproduct generated in the camphor synthesis process as a raw material, belonging to the technical field of organic synthesis.The byproduct 3-camphene ester generated in the synthesis process of camphor is used as a starting material to prepare high-purity camphorquinone through refining, saponification, dehydrogenation, condensation, hydrolysis and recrystallization steps. The method has the beneficial effects that the value of the byproduct generated in the camphor synthesis process is used, industrial wastes are reduced, wastes are changed into valuables, environmental pressure is reduced, a brand-new path for the synthesis of the camphorquinone is provided, no heavy metals are used in all process steps, truly nontoxic chemical synthesis of the camphorquinone is realized, and the method is an economic and environment-friendly production process.
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Paragraph 0050; 0051
(2019/09/14)
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- A phenanthroline-derived ligand and its complexation with Pd(II): From ligand design, synthesis and Pd(II) complexes structures to its application
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A novel phenanthroline-derived bis-opened-triazine ligand for selective complexation with Pd(ii) over 19 typical metals from HNO3 media was designed based on cavity modulation strategy. Structures of the three species of the Pd(ii) complexes of with the ligand were elucidated by 1H NMR titration isothermal titration calorimetry (ITC) and density functional theory (DFT) studies. ITC test and binding energy calculations demonstrated that the asymmetrical 1:1 Pd(ii)-ligand complex with a monodentate nitrate anion was the most stable among these three species of the Pd(ii) complexes. The excellent kinetics of Pd(ii) extraction with the ligand is due to its optimal conformation completely ready for metal ligation. The enhanced special extraction selectivity and fast extraction rate towards Pd(ii) achieved by the phenanthroline-derived ligand demonstrated that the effective separation of some radionuclides with smaller radius in HLW through cavity modulation strategy is a feasible approach.
- Xu, Lei,Zhang, Anyun,Lu, Yanchao,Yang, Hua,Liu, Ziyang
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p. 99859 - 99866
(2016/11/09)
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- tetrapyrazinoporphyrazine derivatives for photodynamic therapy and manufacturing method therof
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The present invention relates to a tetrapyrazinoporphyrazine derivative for photodynamic therapy, in which various alcohols are substituted in the axial direction of a silicon tetrapyrazinoporphyrazine derivative. Thus, optical properties and solubility according to a solvent are improved and optical characteristics are also improved, so that the tetrapyrazinoporphyrazine derivative can be used as an effective photosensitizer for photodynamic therapy. In addition, the tetrapyrazinoporphyrazine derivative is represented by chemical formula 1.COPYRIGHT KIPO 2016
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Paragraph 0071; 0072; 0073; 0074
(2017/01/31)
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- SELECTIVELY POLYMERIZABLE COMPOSITIONS AND METHODS OF USE IN VIVO
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Otologic materials and methods are provided. For example, a cell-adhesive, biodegradable hydrogel scaffold loaded with time-released drugs for repairing chronic tympanic membrane perforations is disclosed, methods of making same and administering same are provided. This hydrogel may promote vascular in-growth and epithelial cell growth of the tympanic membrane with the purpose of closing the perforation and providing a barrier between the external and middle ear. The hydrogel is initially a liquid polymer that only gels upon exposure to specific conditions, such as exposure to light. This scaffold may simultaneously induce repair of the tympanic membrane while preventing or alleviating middle ear infection, thus filling a void in current tympanic membrane perforation therapies.
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Page/Page column
(2015/04/28)
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- Photocatalytic degradation of water taste and odour compounds in the presence of polyoxometalates and TiO2: Intermediates and degradation pathways
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Geosmin (GSM) and 2-methylisoborneol (MIB) are produced by several species of cyanobacteria and actinomycetes. These compounds can taint water and fish causing undesirable taste and odours. Studies have shown that GSM/MIB are resistant in standard water treatments. Polyoxometalates (POM) are efficient photocatalysts in the degradation and mineralization of a great variety of organic pollutants, presenting similar behaviour with the widely published titanium dioxide (TiO2). Photocatalytic degradation of GSM and MIB under UV-A light in the presence of a characteristic POM photocatalyst, SiW 12O404-, in aqueous solution has been studied and compared with the photodegradation by TiO2 suspensions. GSM and MIB are effectively degraded in the presence of both photocatalysts. Addition of OH radical scavengers (KBr and tertiary butyl alcohol, TBA) retards the photodegradation rates of both compounds, suggesting that photodegradation mechanism takes place via OH radicals. Intermediates identified using GC-MS in the case of GSM and MIB, are mainly identical in the presence of both photocatalysts, also suggesting a common reaction mechanism. Possible photocatalytic degradation pathway for both GSM and MIB is proposed.
- Fotiou, Theodora,Triantis, Theodoros M.,Kaloudis, Triantafyllos,Papaconstantinou, Elias,Hiskia, Anastasia
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- 1H NMR-based kinetic-mechanistic study of the intramolecular trans-esterification of 2-exo-3-exo-dihydroxybornane monoacrylate esters
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A 1H NMR study of the acid-catalyzed, intramolecular trans-esterification between isomeric 2-exo-3-exo-dihydroxybornane monoacrylate esters has afforded insights into the reaction mechanism and permitted the determination of kinetic and thermodynamic parameters for the pseudo-first-order processes.
- Duggan, Andrew R.,Mciteka, Lulama P.,Lobb, Kevin A.,Kaye, Perry T.
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p. 140 - 144
(2013/07/26)
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- New chiral iodooxazoline catalysts for the I(III)-mediated α-tosyloxylation of ketones: Refining the stereoinduction model
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A new family of iodooxazoline catalysts, derived from widely available chiral ketones (menthone and camphor), was developed to promote the iodine(III)-mediated α-tosyloxylation of ketone derivatives. The reaction conditions to achieve the direct formation
- Therien, Marie-Eve,Guilbault, Audrey-Anne,Legault, Claude Y.
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p. 1193 - 1197
(2013/10/22)
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- METHOD FOR MANUFACTURING ESTER
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The present invention relates to a method for manufacturing an ester from a ketone or an aldehyde, which is a reactive substrate, by a Baeyer-Villiger oxidation reaction using hydrogen peroxide, and in this method, as a catalyst, M(BAr4)n, which is a metal borate, is used (M represents an alkali metal or an alkaline earth metal; Ar represents an aryl; and n is the same number as the valence of M). For example, when cyclohexanone was used as the reactive substrate, and Sr[B(3,5-CF3C6H3)4]2 was used as the catalyst, ε-caprolactone was obtained at an isolated yield of 82%.
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Paragraph 0070; 0074; 0090
(2013/08/28)
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- Camphor-based Schiff base ligand SBAIB: An enantioselective catalyst for addition of phenylacetylene to aldehydes
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A series of Schiff base ligands were synthesized from (1R)-camphor. Under the optimal conditions, (+)-SBAIB-a, 10 was found to be an excellent catalyst for the enantioselective addition of phenylacetylene to various aldehydes without utilizing either achiral additives or Ti(OiPr)4. This approach yielded (R)-propargylic alcohols in extremely high yields (up to 99%) and excellent enantioselectivities (up to 92%). The corresponding (S)-propargylic alcohols were synthesized in good to high enantioselectivities (up to 91%) and excellent yields (up to 99%) using (-)-SBAIB-a, 41.
- Boobalan, Ramalingam,Chen, Chinpiao,Lee, Gene-Hsian
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scheme or table
p. 1625 - 1638
(2012/03/22)
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- Synthesis of novel 3-hydroxy-3-pyridylcamphor derivatives
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The synthesis of a series of five novel precursor compounds derived from (R)-(+)-camphor is reported. From these precursors, a further four novel pyridyl alcohol ligands were synthesized. The molecules represent the first reported examples where the pyridyl and hydroxyl moieties are pendant on the C3 position of the camphor skeleton. The regioselective synthesis was investigated and an efficient method was identified. The final ligands were obtained in moderate yield with absolute regio- and stereoselective control. The molecules were screened as catalysts in the alkylation of aldehydes with diethylzinc in order to compare the new arrangement of donor groups with previously reported results obtained with C2 pendant ligands. The results demonstrated a significant improvement for the synthesizedC3pendant ligands over previousC2examples with moderate yields and up to 85 % ee being obtained.
- Boyle, Grant A.,Govender, Thavendran,Kruger, Hendrik G.,Maguire, Glenn E.M.
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experimental part
p. 113 - 123
(2011/08/06)
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- Utilizing terpene derivatives in the synthesis of annulated terpene-imidazoles with application in the nitroaldol reaction
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Two classes of terpene derivatives (diketones and monoximes) were condensed into annulated terpene-imidazoles using two general methods. Method A, involving the condensation of terpene diketones and aldehydes, gave lower yields than Method B, which employed terpene monoximes and amines. The mechanism of Method B is discussed. Using both methods, overall 11 new imidazole ligands were synthesized and fully characterized. The molecular structures of the side product 16 and intermediate 4b were also characterized by X-ray analysis. Regarding 1a, N-methylation and subsequent ortho-lithiation and quenching with diphenylphosphinechloride were proven. The synthesized ligands were tested in the Henry reaction providing reaction times 24-72 h and enantioselectivities up to 32% especially for the pyridine 2-substituted ligands 1c, 2c, 3b and N,P-ligand 17.
- Kulhanek, Jiri,Bures, Filip,Simon, Petr,Bernd Schweizer
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scheme or table
p. 2462 - 2469
(2009/04/11)
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- Asymmetric synthesis of N-1-(heteroaryl)ethyl-N-hydroxyureas
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The asymmetric synthesis of two 5-lipoxygenase inhibitors (R)-N-1-(benzofuran-2-yl)ethyl-N-hydroxyurea, 99% ee, and (R)-N-1-(benzo[b]thiophen-2-yl)ethyl-N-hydroxyurea, 95% ee, is described. The enantioselective reduction of 1-(benzofuran-2-yl)ethanone oxime O-benzyl ether and 1-(benzo[b]thiophen-2-yl)ethanone oxime O-benzyl ether with borane oxazaborolidine, generated from (1R,2S,3R,4S)-3-amino-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol, was used for the formation of the stereogenic centres.
- Bosiak, Mariusz J.,Krzeminski, Marek P.,Jaisankar, Parasuraman,Zaidlewicz, Marek
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p. 956 - 963
(2008/09/21)
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- A new chiral organosulfur catalyst for highly stereoselective synthesis of epoxides
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A new chrial organosulfide was synthesized through an unexpected Wagner-Meerwein rearrangement. This organosulfide could catalyze the epoxidation reaction of various aromatic aldehydes smoothly with benzyl bromide to give trans-diaryl epoxides in satisfactory yields (60-84%) with excellent diastereoselectivities (trans:cis=95:5-100:0) and good to excellent enantioselectivities (86-96% ee).
- Gui, Yuan,Li, Jian,Guo, Chang-Shan,Li, Xin-Liang,Lu, Zhi-Feng,Huang, Zhi-Zhen
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supporting information; experimental part
p. 2483 - 2487
(2009/09/08)
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- Efficient chemoselective mild deprotection of S,S-and S,O-acetals and ketals with electrophilic halogens
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A novel and simple method for the chemoselective deprotection of S,S- and S,O-acetals and ketals in the presence of their O,O-analogs with electrophilic halogens to their corresponding carbonyl compounds is described using N-bromosuccinimide, N-chlorosuccinimide, 2,4,4,6-tetrabromo-2,5-cyclohexen-1- one, trichlorocyanuric acid, or molecular bromine in aqueous acetonitrile. The use of these reagents in the presence of hydrated silica gel provide efficient, novel, and mild procedures for the deprotection of cyclic and acyclic O,O-, S,S-, and S,O-acetals and ketals in excellent yields in short reaction times. Copyright Taylor & Francis Group, LLC.
- Shaterian, Hamid Reza,Hadadzadeh, Hassan
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p. 1059 - 1071
(2007/10/03)
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- Microwave-assisted selenium dioxide oxidation of camphor derivatives to α-dicarbonyl compounds and oxoimines
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Camphor-derived α-dicarbonyl compounds and 3-oxo-camphorsulfonylimine have been synthesized from the corresponding ketones or sulfonylimine by microwave-assisted oxidation with selenium dioxide. Compared to the classical reaction conditions, good yields were obtained in much shorter reaction times. Additionally, the selenium precipitation is more quantitative, and its removal from the reaction mixture is easier. Copyright Taylor & Francis Group, LLC.
- Belsey, Sarah,Danks, Timothy N.,Wagner, Gabriele
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p. 1019 - 1024
(2007/10/03)
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- Catalytic and chemoselective deprotection of S,S- and S,O-acetals and ketals in the presence of their O,O-analogs with electrophilic halogens under neutral conditions
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A novel and catalytic method is described for the selective deprotection of S,S- and S,O-acetals and ketals in the presence of their O,O-analogs to their corresponding carbonyl compounds based on the use of N-bromosuccinimide (NBS), N-chlorosuccinimide (NCS), 2,4,4,6-tetrabromo-2,5-cyclohexadiene-1-one (TABCO), trichlorocyanuric acid (TCCA) or molecular bromine as sources of electrophilic halogens in the presence of DMSO as the source of oxygen in CHCl3.
- Iranpoor, Nasser,Firouzabadi, Habib,Shaterian, Hamid Reza
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p. 4769 - 4773
(2007/10/03)
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- Chiral tricyclic iminolactone derived from (1R)-(+)-camphor as a glycine equivalent for the asymmetric synthesis of α-amino acids
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The development of a highly efficient and stereoselective methodology for the preparation of α-amino acids is described. The chiral template, tricyclic iminolactone 7, was synthesized from (1R)-(+)-camphor in five steps in 50% overall yield. Alkylation of iminolactone 7 afforded the α-monosubstituted products in good yields (74-96%) and excellent diastereoselectivities (>98%). Hydrolysis of the alkylated iminolactones furnished the desired α-amino acids in good yields and enantioselectivities with nearly quantitative recovery of the chiral auxiliary 4.
- Xu, Peng-Fei,Chen, Yuan-Shek,Lin, Shu-I,Lu, Ta-Jung
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p. 2309 - 2314
(2007/10/03)
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- The practical synthesis of a uterine relaxant, Bis( 2-{[(2S)-2-({(2R)-2-hydroxy-2-[4-hydroxy-3-(2-hydroxyethyl) -phenyl]ethyl}amino) -1,2,3,4-tetrahydronaphthalen-7-yl]oxy}-N,N-dimethylacetamide) sulfate (KUR-1246)
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The synthetic route for a uterine relaxant, bis(2-{[ (2S)-2-({(2R)-2-hydroxy-2-[4-hydroxy-3- (2-hydroxyethyl)-phenyl]ethyl}amino) -1,2,3,4-tetrahydronaphthalen-7-y1]oxy}-N,N-dimethylacetamide) sulfate (KUR-1246), was established by the coupling of optically active components, the bromohydrin 14 and the amine 24. We now describe the practical synthesis of these two optically active components. Bromohydrin 14 was obtained by the asymmetric borane reduction of the prochiral phenacyl bromide 13 using a catalyst prepared from aluminum triethoxide and a chiral amino alcohol. The other optically active component 24 was prepared from (S)-AMT.
- Yanagi, Takashi,Kikuchi, Ken,Takeuchi, Hideki,Ishikawa, Takehiro,Nishimura, Toshihiro,Yamamoto, Iwao
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p. 1018 - 1023
(2007/10/03)
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- Method for the synthesis of a taxane intermediate
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A process for the preparation of a compound having the formula: in which a compound having the formula: is treated with a base and a silylating agent.
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- Asymmetric Conversion of Arenechromium Complexes to Functionalized Cyclohexenones: Progress toward Defining an Optimum Chiral Auxiliary
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An investigation into the asymmetric synthesis of 5-substituted cyclohexenones via nucleophile addition to (alkoxyarene)chromium tricarbonyl complexes is described. Diastereoselectivity during the nucleophile addition step was achieved using alkoxy substituents derived from terpenoid substrates as chiral auxiliaries. Selectivities as high as 24:1 were obtained when 2-phenylisoborneol was used as the chiral auxiliary and as high as 17:1 using 3,3-(ethylenedioxy)isoborneol. The absolute stereochemistry of the major products was assigned by Mosher's method, after their conversion to the corresponding cyclohexenol. A study of the temperature dependence of the nucleophile addition to alkoxytoluene complexes revealed a thermodynamic preference for addition ortho to the ether substituent.
- Pearson, Anthony J.,Gontcharov, Alexander V.
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p. 152 - 162
(2007/10/03)
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- Phospho-transfer catalysis on the asymmetric hydrophosphonylation of aldehydes
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We report here a precise, in situ 31P{1H}-NMR method of assaying enantiopurity of α-hydroxyphosphonate esters, the products of the carbonyl hydrophosphonylation (Pudovik) reaction. This method is based upon a diazaphospholidine chiral derivatising agent (CDA) which satisfies all of the criteria for a precise assay; (i) derivatisation of α-hydroxyphosphonate esters is both rapid and clean, (ii) kinetic resolution is absent and (iii) 31P{1H} chemical shift dispersions are excellent (> 5ppm). Calibration of this assay has been achieved by cross-referencing the 31P{1H}-NMR signals obtained for the CDA-derivatised ester of (MeO)2PC=O)CHPh(OH) to optical rotation measurements from scalemic material obtained upon lipase catalysed hydrolysis (F-AP 15, Rhizopus oryzae) of (MeO)2P(=O)CHPh(OAc). Analysis of NMR chemical shift and coupling parameters for a closely related series of derivatised α-hydroxyphosphonate esters support further configuration assignments on the basis of inference. We report also on the configurational stability of α-hydroxyphosphonate esters in the presence of acids, organonitrogen bases and metal salts. 2H-labelling and carbonyl crossover experiments reveal that low levels of epimerisation (α) of α-hydroxyphosphonate esters is possible under certain conditions of catalysis and within certain limits. A design strategy for the construction of catalyst systems in the Pudovik reaction is outlined based upon a combination of Lewis acidic (E) and Lewis basic (N) sites. Four types of catalyst are outlined, members of two distinct Classes I and II according to the nature of the acid and base sites, along with our investigations of representative examples of each Class. A variety of Class I.1 systems based on β-amino alcohols (one hydrogen bonding E site and one organonitrogen N site), have been assayed in the model reaction between (MeO)2P(O)H and PhCHO. Results suggest that catalysis of the Pudovik reaction is clean and efficient in certain cases but that catalytic activity is strongly dependent upon the nature of the basic (N) nitrogen centre. Moreover, only low levels ( 50% more strongly (K11 0.53 mol-1 dm3) than dimethyl-H-phosphonate (K11 0.34 mol-1 dm3, 298 K) and to catalyse the hydrophosphonylation reaction between these two substrates with a second order rate constant comparable to that of triethylamine (both k2 5.9 × 10-2 mol-1 dm3 h-1, 293 K). However, one of the major limitations of this model is that competitive product inhibition dominates after some 15 turnovers (75% completion). Model studies reveal that hydrophosphonylation catalysis via a nitrogen Lewis base is accelerated up to 10-fold upon the introduction of [Zn(OSO2CF3)2] as co-catalyst. Consequently, Class II.1 systems employ metal salts [Zn(OSO2CF3)2] as Lewis acidic E sites and chiral co-catalysts capable of binding to the metal and also acting as Lewis basic N sites. Such systems catalyse the addition of (MeO)2P(O)H to PhCHO cleanly with modest turnover numbers (2P(O)H to PhCHO to afford (MeO)2P(O)CHPh(OH) with an average turnover rate (over a 1 h reaction time at 298 K) of 115 h-1 compared to ca. 1 h-1 for NEt3 under analogous conditions. Chiral variants are proposed.
- Davies, Stephen R.,Mitchell, Michael C.,Cain, Christopher P.,Devitt, Paul G.,Taylor, Roger J.,Kee, Terence P.
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- Asymmetric Diels-Alder reactions employing modified camphor-derived oxazolidin-2-one chiral auxiliaries
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Transposition of the dormant methyl group from C-1 in chiral oxazolidin-2-one 2 to C-7 in a six step synthetic sequence from (1R)-camphore 5 creates a novel transfigomer 4 with sufficient π-topological bias to induce excellent levels of asymmetric induction in Lewis-acid catalysed Diels-Alder reactions of its α, β-unsaturated carboximide derivatives with cyclopentadiene. Further modification of 4 by replacement of the C-7 methyl group with an ethyl substituent raises the level of diastereoselectivity for the acrylate derivative 11a from 81 to > 95% d.e..
- Banks, Malcolm R.,Blake, Alexander J.,Cadogan,Doyle, Allan A.,Gosney, Ian,Hodgson, Philip K. G.,Thorburn, Paul
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p. 4079 - 4094
(2007/10/03)
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- NOVEL AND EFFICIENT ONE-POT SYNTHESIS OF PHOSPHORUS HETEROCYCLES CONTAINING THE BICYCLOHEPTENE MOIETY
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In a convenient one-pot sequence, treatment of camphorquinone with sodium in dry tetrahydrofuran followed by addition of phosphorodichloridate and phosphorothiodichloridate yields 2-oxo-1,3,2-dioxaphospholes and 2-thioxo-1,3,2-dioxaphospholes, respectively.Similar treatment of 3-phenyliminobornan-2-one with sodium in dry THF followed by addition of phosphorodichloridate and phsphorothiodichloridate yields 2-oxo-1,3,2-oxazaphospholes and 2-thioxo-1,3,2-oxazaphospholes.Key words: Camphorquinone, 3-phenyliminobornan-2-one, phosphorodichloridate, phosphorothiodichloridate, dioxaphospholes, oxazaphospholes.
- Singh, M. S.
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p. 187 - 192
(2007/10/03)
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- A New Oxidation of 3-Bromocamphor to Camphorquinone
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3-Bromocamphor was oxidized in DMSO by bubbling air in the presence of sodium iodide to give camphorquinone quantitatively.The oxidation was found to proceed under mild conditions by a radical mechanism.
- Hattori, Kazuyuki,Yoshida, Takashi,Rikuta, Ken-ichi,Miyakoshi, Tetsuo
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p. 1885 - 1888
(2007/10/02)
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- Applications of novel camphor-derived chiral auxiliaries in the α-benzylation of carboxylic esters
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The diastereoselectivity of α-benzylation of carboxylic esters of 2,2- and 3,3-propylenedioxy alcohols derived from camphor, and related alcohols, has been investigated and the conformational implications have been explored using computer modelling techni
- Kaye, Perry T.,Ravindran, Swarnam S.
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- Stereoselectivity in the α-benzylation of camphor-derived carboxylic esters
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The influence of substitution on the stereoselectivity of α-benzylation of chiral carboxylic esters, obtained by acylation of 3,3-ethylenedioxy-2-exo-hydroxybornane, has been investigated.
- Kaye, Perry T.,Ravindran, Swarnam S.
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- Attempted Kinetic Resolution of 1,2-Diols by Camphorquinone: Generation of (R)-(Chloromethyl)oxirane
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The epichlorohydrin (R)-(chloromethyl)oxirane has been prepared from rac-3-chloropropane-1,2-diol by means of the chiral ketone D-camphorquinone (1,7,7-trimethylbicycloheptane-2,3-dione).These reactions lead to intermediate dioxolanes which can be converted directly into oxiranes.This conversion was effected by reduction of the C-2-ketone of the dioxolane intermediate with sodium borohydride prior to reaction with hydrogen bromide-acetic acid followed by treatment of the resulting acetoxy bromide with sodium ethane-1,2-diolate.The diastereoselective formation of other dioxolanes was also investigated by reaction of D-camphorquinone with ethane-1,2-diol, propane-1,2-diol, and 3,3-dimethylbutane-1,2-diol.
- Ellis, Martin K.,Golding, Bernard T.,Maude, Antony B.,Watson, William P.
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p. 747 - 755
(2007/10/02)
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- CHIRAL α,β-UNSATURATED OXAZOLINES IN THE ASYMMETRIC DIELS-ALDER REACTION
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α,β-Unsaturated oxazolines derived from (+)-camphor become powerful dienophiles in asymmetric Diels-Alder reaction after activation with trifluoroacetic anhydride.
- Pouilhes, A.,Uriarte, E.,Kouklovsky, C.,Langlois, N.,Langlois, Y,et al.
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p. 1395 - 1398
(2007/10/02)
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- 3-Hydroxyiminocamphornitrimine and Camphorquinone Dinitrimine, Compounds Previously Described as N-Nitro-3-nitrosocamphorenamine and N-Nitro-N,3-dinitrosocamphorenamine. Crystal Structue of Camphorquinone Dinitrimine
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The structures of 3-hydroxyiminocamphornitrimine (2) and camphorquinone dinitrimine (7), previously described by some of us as nitroso derivatives (see title), have been proven on the basis of 13C n. m. r. spectral data and chemical transformations.The crystal structure of (7) showed that the configuration of 2- and 3-nitrimino groups is syn and anti to the C(2)-C(3) bond, respectively, and the nitro groups planes being nearly perpendicular to the N=C-C=N system.
- Ranise, Angelo,Bondavalli, Francesco,Schenone, Pietro,Sancassan, Fernando,Mugnoli, Angelo
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p. 2157 - 2182
(2007/10/02)
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- Structural Effects Affecting Hydration of 1,2-Diones Studied by Linear-Sweep Voltammetry
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Linear-sweep voltammetry was used for determination of values KdCO = and KdCO = +R'>+)R'> for some aliphatic and alicyclic 1,2-diketones.Values obtained were compared with data obtained from UV and NMR spectra.Dc polarographic data were used to choose the most reliable value.In all cases, the protonated form predominating in solutions of sulfuric acid is less strongly hydrated than the unprotonated form.The effect of ring size on the hydration in polycyclic species is discussed.Steric hindrance of the hydration due to the 7- and possibly the 1-methyl group in 2,3-camphorquinone has been confirmed.
- Segretario, James P.,Sleszynski, Neal,Partch, Richard E.,Zuman, Petr,Horak, Vaclav
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p. 5393 - 5396
(2007/10/02)
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- UNTERSUCHUNGEN AN DIAZOVERBINDUNGEN UND AZIDEN-LIII. ABFANGREAKTIONEN INSTABILER AZOMETHINIMIN-DIPOLE MIT ETHANOL
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The reaction of the diazo compounds 1a-o with 4-phenyl-1,2,4-triazolin-3,5-dione (2) in dichloromethane-ethanol leads to the urazoles 5a-o; they arise from the primarily formed unstable azomethinimine dipoles 4a-o by ethanol addition.Acidic hydrolysis of 5k and 5o yields the α-diketones 8 and 10 besides 4-phenyl urazole (9).Bistriazolindinones (13a,b) react analogously with diazo compounds (1l, m) in the presence of ethanol to give the bisurazoles 14a-c.
- Theis, W.,Bethaeuser, W.,Regitz, M.
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p. 1965 - 1972
(2007/10/02)
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- Kinetic Resolution of 1,2-Diols with D-Camphorquinone; Preparation of (R)-(Chloromethyl)oxirane
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Acid-catalysed reaction of D-camphorquinone with racemic 1,2-diols (e.g. 3-chloropropane-1,2-diol) under kinetically controlled conditions yields a predominant diastereoisomeric acetal, that can be easily converted into an optically pure epoxide.
- Ellis, Martin K.,Golding, Bernard T.,Watson, William P.
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p. 1600 - 1602
(2007/10/02)
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- MECHANISM OF THE PHOTOOXIDATION OF AND PHOTOEPOXIDATION WITH CYCLIC alpha -DIKETONES.
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The photooxidation of phenanthrenequinone (PhQ) under oxygen afforded diphenic acid and its peroxy acid, while acenaphthenequinone (AcQ) predominantly yielded 1,8-naphthalenedicarboxylic anhydride. The photolysis of PhQ or AcQ in the presence of olefins afforded predominantly 1:1 cycloadducts and the photoepoxidation was a very minor one accompanying significant amount of C-C clevage of olefins. These results show that the photoreaction of PhQ or AcQ with olefins is very fast and competitive with the quenching and/or reaction with oxygen. The photoepoxidation of stilbene in the presence of dimethyl sulfoxide resulted in a high selectivity ( greater than 98%) for the trans-epoxide.
- Sawaki
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p. 3464 - 3470
(2007/10/02)
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- Reduction by a Model of NAD(P)H. 32. Stereoselective Reduction of Camphoroquinone by a Chiral NAD(P)H Model
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(+)-, (-)-, and racemic camphoroquinones (CQ) were reduced by each of four NAD(P)H-models such as N-(α-methylbenzyl)-1-propyl-2,4-dimethyl-1,4-dihydronicotinamide (Me2PNPH) in the presence of magnesium ion in acetonitrile with a view to elucidating the intermolecular arrangement in the transition state for asymmetric reduction.Partial rate factors for each attacking mode were calculated.Electronegative substituents in the substrate prefer to facing the carbamoyl group in Me2PNPH, which is the most important factor determining the stereochemical course of the reduction. 1-Methyl group in CQ has a tendency to interfere with the dihydropyridine moiety in Me2PNPH approaching the C2-carbonyl group in CQ.This interference is more important for the selectivity than the intrinsic exo/endo reactivity difference.
- Ohno, Atsuyoshi,Goto, Takehiko,Nakai, Jun-ichi,Oka, Shinzaburo
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p. 3478 - 3481
(2007/10/02)
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- PHOTOSENSITIZED OXYGENATION OF 3-DIAZOCAMPHOR
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Photosensitized oxygenation of 3-diazocamphor gave camphorquinone and camphoric anhydride in benzene.The yield of camphoric anhydride did not depend on the concentration of added camphorquinone or of diazocamphor.When the reaction was carried out in acetonitrile or benzonitrile, amide 7 or 8 was produced.The formation of amide strongly supports the intermediacy of carbonyl oxide.
- Okada, Keiji,Mukai, Toshio
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p. 359 - 360
(2007/10/02)
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- Conversion of Thiocarbonyl Compounds into their Corresponding Oxo-derivatives using Benzeneseleninic Anhydride
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A series of thiocarbonyl compounds including xanthates, thioesters, thioureas, thiocarbonates, and thiones have been converted into their oxo-analogues by treatment with benzeneseleninic anhydride in tetrahydrofuran at room temperature.Except for readily enolised thiones where further oxidation can take place, the method works well and compares favourably with other literature procedures.One example of a selenocarbonyl ester was likewise converted efficiently into the corresponding ester.
- Cussans, Nigel J.,Ley, Steven V.,Barton, Derek H. R.
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p. 1650 - 1653
(2007/10/02)
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