- Method used for direct synthesis of epoxy compounds from alcohol
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The invention discloses a method used for direct synthesis of an epoxy compounds from an alcohol. According to the method, an alcohol is taken as a raw material, Swern oxidation is adopted to synthesize an aldehyde, a bromo-hydrocarbon and an alkali are added into the aldehyde directly to construct epoxy functional groups, and generate the epoxy compound. According to the method, one-pot method is adopted to realize direct epoxidation of the alcohol, the synthesis route is simple, the preparation process is easy to control, no catalyst is needed in the process, substrate suitable range is wide, reagents are cheap and easily available, preparation conditions are mild, reaction yield is high, and the method is suitable for synthesis of epoxy compounds.
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Paragraph 0140-0147
(2019/10/08)
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- A non-heme iron(III) complex with porphyrin-like properties that catalyzes asymmetric epoxidation
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In this report, we describe an iron(III) complex containing a carbazole-based tridentate ligand that catalyzes highly enantioselective asymmetric epoxidation of (E)-alkenes at room temperature. The non-heme iron(III) complex has a five-coordinated trigonal-bipyramidal structure, and its two-electron oxidized state has the similar electronic structure as that of iron porphyrins.
- Niwa, Takashi,Nakada, Masahisa
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p. 13538 - 13541
(2012/10/08)
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- New camphor-derived selenonium ylides: Enantioselective synthesis of chiral epoxides
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Optically pure selenonium salts 3 as the precursors of two new chiral selenonium ylides 4 can be synthesized stereoselectively from natural d-camphor in good yields. It is found that the reaction of the selenonium salt 3b, an aldehyde, and potassium tert-butoxide can take place smoothly in ?one-pot' via the formation of selenonium ylide 4b, to give chiral trans-diaryl epoxides 5 in good yields with good diastereoselectivities and enantioselectivities. CSIRO 2005.
- Li, Xin-Liang,Wang, Yi,Huang, Zhi-Zhen
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p. 749 - 752
(2007/10/03)
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- A novel and highly efficient asymmetric synthesis of epoxides via chiral telluronium ylides
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The one-pot reaction of telluronium salt 8, aldehyde, and potassium tert-butoxide proceeded smoothly via chiral benzyl telluronium ylide, producing trans-(2S,3S)-diaryl epoxides with good yields as well as excellent diastereoselectivities and enantioselectivities (up to 99% ee). Georg Thieme Verlag Stuttgart.
- Ou, Wen-Hua,Huang, Zhi-Zhen
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p. 2857 - 2860
(2007/10/03)
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- Design of sulfides with a locked conformation as promoters of catalytic and asymmetric sulfonium ylide epoxidation
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A new generation of 2,5-dimethylthiolanes with a locked conformation was developed to promote the asymmetric addition of chiral sulfonium ylides to aldehydes. The novel chiral sulfur derivative 4 succeeded the synthesis of trans-stilbene oxide derivatives with enantiomeric ratios ranging from 95:5 to 98:2. This user-friendly organocatalytic process proved to be efficient with 20-10% of sulfide 4 in 1 or 2 days of reaction. An insight into the ylide intermediate conformation is given on the basis of a computational ab initio study.
- Davoust, Marion,Briere, Jean-Francois,Jaffres, Paul-Alain,Metzner, Patrick
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p. 4166 - 4169
(2007/10/03)
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- A new protocol for the in situ generation of aromatic, heteroaromatic, and unsaturated diazo compounds and its application in catalytic and asymmetric epoxidation of carbonyl compounds. Extensive studies to map out scope and limitations, and rationalization of diastereo- and enantioselectivities
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A variety of metalated tosylhydrazone salts derived from benzaldehyde have been prepared and were reacted with benzaldehyde in the presence of tetrahydrothiophene (THT) (20 mol %) and Rh2(OAc)4 (1 mol %) to give stilbene oxide. Of the lithium, sodium, and potassium salts tested, the sodium salt was found to give the highest yield and selectivity. This study was extended to a wide variety of aromatic, heteroaromatic, aliphatic, α,β-unsaturated, and acetylenic aldehydes and to ketones. On the whole, high yields of epoxides with moderate to very high diastereoselectivities were observed. A broad range of tosylhydrazone salts derived from aromatic, heteroaromatic, and α,β-unsaturated rated aldehydes was also examined using the same protocol in reactions with benzaldehyde, and again, good yields and high diastereoselectivities were observed in most cases. Thus, a general process for the in situ generation of diazo compounds from tosylhydrazone sodium salts has been established and applied in sulfur-ylide mediated epoxidation reactions. The chiral, camphor-derived, [2.2.1] bicyclic sulfide 7 was employed (at 5-20 mol % loading) to render the above processes asymmetric with a range of carbonyl compounds and tosylhydrazone sodium salts. Benzaldehyde tosylhydrazone sodium salt gave enantioselectivities of 91 ± 3% ee and high levels of diastereoselectivity with a range of aldehydes. However, tosylhydrazone salts derived from a range of carbonyl compounds gave more variable selectivities. Although those salts derived from electron-rich or neutral aldehydes gave high enantioselectivities, those derived from electron-deficient or hindered aromatic aldehydes gave somewhat reduced enantioselectivities. Using α,β-unsaturated hydrazones, chiral sulfide 7 gave epoxides with high diastereoselectivities, but only moderate yields were achieved (12-56%) with varying degrees of enantioselectivity. A study of solvent effects showed that, while the impact on enantioselectivity was small, the efficiency of diazo compound generation was influenced, and CH3CN and 1,4-dioxane emerged as the optimum solvents. A general rationalization of the factors that influence both relative and absolute stereochemistry for all of the different substrates is provided. Reversibility in formation of the betaine intermediate is an important issue in the control of diastereoselectivity. Hence, where low diastereocontrol was observed, the results have been rationalized in terms of the factors that contribute to the reduced reversion of the syn betaine back to the original starting materials. The enantioselectivity is governed by ylide conformation, facial selectivity in the ylide reaction, and, again, the degree of reversibility in betaine formation. From experimental evidence and calculations, it has been shown that sulfide 7 gives almost complete control of facial selectivity, and, hence, it is the ylide conformation and degree of reversibility that are responsible for the enantioselectivity observed. A simple test has been developed to ascertain whether the reduced enantioselectivity observed in particular cases is due to poor control in ylide conformation or due to partial reversibility in the formation of the betaine.
- Aggarwal, Varinder K.,Alonso, Emma,Bae, Imhyuck,Hynd, George,Lydon, Kevin M.,Palmer, Matthew J.,Patel, Mamta,Porcelloni, Marina,Richardson, Jeffery,Stenson, Rachel A.,Studley, John R.,Vasse, Jean-Luc,Winn, Caroline L.
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p. 10926 - 10940
(2007/10/03)
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- Process for the preparation of an oxirane, aziridine or cyclopropane
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A process for the preparation of an oxirane, aziridine or cyclopropane of formula (I), wherein X is oxygen, NR4or CHR5; R1is hydrogen, alkyl, aryl, heteroaromatic, heterocyclic or cycloalkyl; R2is hydrogen, alkyl, aryl, heteroaromatic, CO2R8, CHR14NHR13, heterocyclic or cycloalkyl; or R1and R2join together to form a cycloalkyl ring; R3and R10are, independently, hydrogen, alkyl, aryl, heteroaromatic, CO2R8, R83Sn, CONR8R9, trialkylsilyl or triarylsilyl; R4is an electron withdrawing group; R5is alkyl, cycloalkyl, aryl, heteroaromatic, SO2R8, SO3R8, COR8, CO2R8, CONR8R9, PO(R8)2, PO(OR8)2or CN; R8and R9are independently alkyl or aryl; and R13and R14are independently hydrogen, alkyl or aryl is provided. The process comprises degrading a compound of formula (II), (IIa), (IIb) or (IIc): wherein R3and R10are as defined above; Y is a cation; depending on the nature of Y, r is 1 or 2; and L is a suitable leaving group, to form a diazo compound. The diazo compound is reacted with a suitable transition metal catalyst, and the product thereof reacted with a sulphide of formula SR6R7, wherein R6and R7are independently alkyl, aryl or heteroaromatic, or R6and R7join together to form an optionally substituted ring which optionally includes an additional heteroatom. This product is then reacted with an aldehyde, ketone, imine or alkene.
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- Highly stereoselective synthesis of trans-diaryl epoxides via semi-stabilised telluronium ylide
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Benzyldibutyltelluronium bromide can react with LDA to form benzyldibutyltelluronium ylide in situ, followed by the reaction with aromatic aldehydes, developed a novel method for the stereoselective synthesis of trans-diaryl epoxides.
- Wang, Lei,Huang, Zhizhen
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p. 305 - 306
(2007/10/03)
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- Experimental evidence for multiple oxidation pathways in the (salen)Mn-catalyzed epoxidation of alkenes
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The substrate electronic effects on the selectivity in the catalytic epoxidation of para-substituted cis stilbenes 2a-i were investigated by using (R,R)-[N,N′-bis(3,5-di-tBu-salicylidene)-1,2-cyclohexanediamine] manganese(III) chloride 1 in benzene as the catalyst with iodosobenzene as the terminal oxidant. A Hammett study of the selectivity results reveals a stronger electrophilic character than previously assumed in the (salen)Mn-catalyzed reaction. In general, the best correlations with the experimental values were obtained by using the Hammett σ+ values, which gave ρ = -1.37 for the rate of cisepoxide formation and ρ = -0.43 for the rate of the stepwise process leading to the corresponding trans product. The reaction involves two separate pathways as indicated also by the competitive breakdown of the intermediate on the path to trans epoxide for methoxy-substituted substrates. The asynchronicity in the concerted pathway leading to cis epoxide is apparent for 4-methoxy-4′-nitrostilbene, which yields cis epoxide with 75% ee entirely as a result of electronic effects.
- Linde, Christian,Koliai, Nordine,Norrby, Per-Ola,Akermark, Bjoern
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p. 2568 - 2573
(2007/10/03)
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- Asymmetric epoxidation of aldehydes catalyzed by new C2-symmetrical chiral sulfide
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Asymmetric synthesis of chiral epoxides from various aldehydes with benzyl bromide was investigated using new C2-symmetrical chiral sulfides, which were readily prepared from (R,R)-tartaric acid.
- Ishizaki, Miyuki,Hoshino, Osamu
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p. 1399 - 1402
(2007/10/03)
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- Catalytic asymmetric synthesis of epoxides from aldehydes using sulfur ylides with in situ generation of diazocompounds
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A practical, general, and convergent to epoxides with control of the relative and absolute stereochemistry has been achieved by generating the reactive intermediate (the diazo compound) in situ from tosylhydrazone salts (see scheme, PTC = phase-transfer catalyst, Ts = toluene-4-sulfonyl). High yields (58-82%), high d.r. (88:12-98:2), and high ee values (87-94%) have been obtained using a new class of stable chiral sulfides at low catalyst loading (5 mol%) and [Rh2(OAc)4] (0.5 mol%).
- Aggarwal, Varinder K.,Alonso, Emma,Hynd, George,Lydon, Kevin M.,Palmer, Matthew J.,Porcelloni, Marina,Studley, John R.
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p. 1430 - 1433
(2007/10/03)
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- Preparation of a novel, camphor-derived sulfide and its evaluation as a chiral auxiliary mediator in asymmetric epoxidation via the Corey-Chaykovsky reaction
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Sulfonium ylide-mediated asymmetric one-pot synthesis of optically active epoxides from aldehydes and bromides via the Corey-Chaykovsky reaction is described. The optically pure chiral sulfide was readily prepared from natural camphor via thiabutadiene Diels-Alder cycloaddition, followed by LiAlH4 reduction and hydrogenation of the cycloadduct.
- Saito, Takao,Akiba, Daisuke,Sakairi, Masao,Kanazawa, Shintaro
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- Bifunctional catalysts for catalytic asymmetric sulfur ylide epoxidation of carbonyl compounds
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Carbonyl epoxidation using diazo compounds mediated by catalytic quantities of sulfide and metal catalyst has been investigated using sulfides linked to the metal catalyst. In this study a range of bisoxazolines with pendant sulfides were tested in the as
- Aggarwal, Varinder K.,Bell, Louise,Coogan, Michael P.,Jubault, Philippe
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p. 2037 - 2042
(2007/10/03)
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- Catalytic asymmetric epoxidation of aldehydes. Optimization, mechanism, and discovery of stereoelectronic control involving a combination of anomeric and cieplak effects in sulfur ylide epoxidations with chiral 1,3-oxathianes
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A range of 1,3-oxathianes based on camphorsulfonic acid have been prepared and tested in the catalytic asymmetric epoxidation of carbonyl compounds. It was found that the 1,3-oxathiane derived from acetaldehyde 5b gave the highest yield and enantioselectivity in the epoxidation process. The enantioselectivity was independent of the solvent and metal catalyst used (although yields were dependent on both). The optimum conditions were applied to a range of aldehydes, and good enantioselectivities and diastereoselectivities were observed. The origin of the enantioselectivity was probed, and in particular the role of the oxygen of the 1,3-oxathiane was investigated. Thus, the sulfur and carbon analogues of the camphorsulfonic acid based 1,3-oxathiane (derived from formaldehyde) were prepared (i.e., 1,3-dithiane and thiane analogues). With this series of analogues the steric effects are minimized so that the electronic effects can be investigated. The series of compounds was reacted in the catalytic cycle with benzaldehyde and gave stilbene oxides with 44% ee (sulfur analogue), 41% ee (1,3-oxathiane), and 20% ee (carbon analogue). Thus, it was concluded that the oxygen of the 1,3-oxathiane exerted a significant electronic effect in controlling the face selectivity of the ylide reactions. This electronic effect was a result of combined anomeric (higher with the sulfur analogue, not present with the carbon analogue) and Cieplak effects. A strong anomeric effect was observed in the X-ray structures of one of the 1,3-oxathianes, and an even greater one was observed in the corresponding sulfoxide (this was used as an electronic analogue of the ylide). The face selectivity of the ylide was believed to be complete in reactions with 5b. The minor enantiomer resulted from reaction of the minor conformer of the ylide, reacting again with high face selectivity. This was proven by using a more substituted diazo compound, which was expected to give much less of the minor conformer. Indeed, reaction with mesityldiazomethane gave the corresponding epoxide in essentially enantiomerically pure form.
- Aggarwal, Varinder K.,Ford, J. Gair,Fonquerna, Sílvia,Adams, Harry,Jones, Ray V.H.,Fieldhouse, Robin
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p. 8328 - 8339
(2007/10/03)
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- Development of a polymer bound Wittig reaction and use in multi-step organic synthesis for the overall conversion of alcohols to β-hydroxyamines
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An efficient combinatorial access to β-hydroxyamines suitable for automation is achieved by the mild oxidation of alcohols to aldehydes by polymer supported perruthenate (PSP), the subsequent clean olefination of the obtained aldehydes by polymer supported Wittig reagents followed by the epoxidation of the olefins by dimethyldioxirane (DMDO), and the final aminolysis of the epoxides with various amines is described.
- Bolli, Martin H.,Ley, Steven V.
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p. 2243 - 2246
(2007/10/03)
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- Process for the preparation of an oxirane, azirdine or cyclopropane
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A process for the preparation of an oxirane, aziridine or cyclopropane of formula (I) wherein, X is oxygen, NR4 or CHR5 ; R1 is hydrogen, alkyl, aryl, heteroaromatic, heterocyclic or cycloalkyl; R2 is hydrogen, alkyl, aryl, heteroaromatic, CO2 R8, CHR14 NHR13, heterocyclic or cycloalkyl; or R1 and R2 join together to form a cycloalkyl ring; R3 is hydrogen, alkyl, aryl, heteroaromatic, CO2 R8, R83 Sn, CONR8 R9 or trimethylsilyl; R4 and R5 are, independently, alkyl, cycloalkyl, aryl, heteroaromatic, SO2 R8, SO3 R8, COR8, CO2 R8, CONR8 R9 or CN, or R4 can also be P(O)(aryl)2 ; R8 and R9 are independently alkyl, aryl or arylalkyl; R13 and R14 are independently hydrogen, alkyl or aryl; the process comprising reacting a mixture of a compound of formula (II), wherein R1, R2 and X are as defined above, and a sulphide of formula SR6 R7, wherein R6 and R7 are independently alkyl, aryl or heteroaomatic, or R6 and R7 join together to form a cycloalkyl ring which optionally includes an additional heteroatom, with either (i) a metallocarbon obtainable by reacting an alkylmetal with a methane derivative of formula CHR3 X'X", wherein R3 is as defined above, and X' and X" are independently, a leaving group, or (ii) a metallocarbon obtainable by reacting a compound of formula (III), (wherein R3 may not be hydrogen) with a suitable organometallic or inorganic reagent.
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- Preparation of enantiomerically enriched (2R,3R)- or (2S,3S)-trans-2,3-diaryloxiranes via camphor-derived sulfonium ylides
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Easily available D-(+)-camphor-derived sulfides 3, 4, 6, and 7 were employed for enantioselective epoxidation via an ylide route. When benzylated or methylated sulfides were used as reagents or mediators for benzylidene transfer, stoichiometric and catalytic epoxidations were realized, respectively. Opposite asymmetric induction was achieved only when sulfides containing exo- (3 and 4) and endo- (6 and 7) alkylthio groups were used. That is, both (+)- and (-)-trans-diaryloxiranes could be obtained in excellent yields and moderate to good ee values under extremely mild conditions from the same chiral pool-derived reagents. A nonbonded interaction between the free OH in the ylides from sulfides (3, 6, and 7) and the carbonyl group of aldehydes controls the approach of the substrates to the ylidic carbon preferentially at one specified face and therefore leads to a more efficient asymmetric induction than that in the case of the ylide from methyl-protected hydroxylated sulfides 4, which cannot cause such an interaction. The same opposite asymmetric induction was also observed in the catalytic reaction with methyl-protected hydroxylated sulfide 4b and unprotected hydroxylated sulfide 3b.
- Li, An-Hu,Dai, Li-Xin,Hou, Xue-Long,Huang, Yao-Zeng,Li, Feng-Wei
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p. 489 - 493
(2007/10/02)
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- Optical Resolution on Regioselectively Carbamoylated Cellulose and Amylose with 3,5-Dimethylphenyl and 3,5-Dichlorophenyl Isocyanates
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The optical resolving ability of two types of regioselectively carbamoylated cellulose and amylose with 3,5-dimethylphenyl and 3,5-dichlorophenyl isocyanates was evaluated.One had 3,5-dimethylphenylcarbamate groups at the 2 and 3 positions and a 3,5-dichlorophenylcarbamate group at the 6 position; the other had 3,5-dichlorophenylcarbamate groups at the 2 and 3 positions and a 3,5-dimethylphenylcarbamate group at the 6 position.In cellulose derivatives, the side chains at the 2,3, and 6 positions seem to interact complicatedly with racemates.On the other hand, in the amylose derivatives, the side chains at the 2 and 3 positions may mainly influence the chiral recognition ability.The optical resolving abilities of the cellulose and amylose derivatives having irregularly either 3,5-dimethylphenyl- or 3,5-dichlorophenylcarbamate groups at the 2,3 and 6 positions were also examined.
- Kaida, Yuriko,Okamoto, Yoshio
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p. 2225 - 2232
(2007/10/02)
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- Chiral sulfur-reagents for the preparation of optically active epoxides
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Acyclic chiral sulfides which could be easily synthesized in both enantiomeric forms leading to poor yields and/or to racemic epoxides, Eliel's oxathiane reagent was used and proved to provide chiral trans diarylepoxides in high yield (70-80%) and enantiomeric purities up to 70-100%, with no rearrangement problems. It was also found that phase-transfer conditions were the easiest and the most efficient for these reactions.
- Solladie-Cavallo,Adib
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p. 2453 - 2464
(2007/10/02)
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- Phase transfer catalyzed reaction of some telluronium salts with aromatic aldehydes
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Under the liquid-liquid phase transfer condition, the reaction of aromatic aldehydes with benzyl dibutyl telluronium bromide were found to give epoxy compounds, while the reactions with p-chlorobenzyl dibutyl telluronium bromide were found to give epoxy compounds or olefins.
- Zhong,Shao,Liu,Lu
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p. 869 - 876
(2007/10/02)
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- Reactions of Carbonyl Compounds with Benzyltrialkylstibonium Bromide mediated by Different Strong Bases
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Reactions of carbonyl compounds with benzyltrialkylstibonium bromide mediated by alkyl-lithium gave homobenzylic alcohols, while mediated by lithium di-isopropylamide (LDA) gave a mixture of an alkene and an epoxide
- Huang, Yao-Zeng,Liao, Yi,Chen, Chen
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- Oxyanionic Substituent Effect on the C-H Insertion of Carbenes. Reaction of Alkoxides with Dichlorocarbene and Chlorophenylcarbene
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The lithium alkoxides of benzylic, allylic, and simple alkyl alcohols were allowed to react with chloroform in the presence of t-BuOLi in THF-hexane to give, in 32-91percent yields, dichloromethylcarbinols, which were produced by the insertion of dichlorocarbene into the α C-H bond of alkoxides but not by the Wittig rearrangement of carbanions of alkyl dichloromethyl ethers.The enhanced reactivity toward dichlorocarbene of the α C-H bond of alkoxides was clearly demonstrated by the high selectivity of the insertion.The potassium alkoxides of a series of analogous alcohols reacted analogously with benzal chloride in the presence of t-BuOK in THF to give the corresponding substituted oxiranes (16-79percent); e.g., the reaction of potassium benzyl oxide gave 2,3-diphenyloxirane (79percent) as a mixture of stereoisomers (trans:cis = 1.0).With 2-phenethoxide, n-octyl oxide, or 2-methoxyethoxide, the corresponding dialkyl acetals of benzaldehyde were also formed in 9, 6, and 6percent yield, respectively, and their formation is explained in terms of nucleophilic attack of alkoxide on chlorophenylcarbene.With trans-crotyl oxide or 2-phenetoxide, 1,3-diphenylpropan-1-one(33percent) and 1-phenylpent-3-en-1-one (6percent) were produced, respectively, as byproducts through the isomerization of the primary product oxiranes.Oxiranes were produced by the insertion of chlorophenylcarbene into the α C-H bond of alkoxides followed by the cyclization of the intermediate 1-substituted 2-chloro-2-phenethyl alkoxide.These reactions provide us with new preparative methods of synthetically useful dichloromethyl carbinols and oxiranes.
- Harada, Toshiro,Akiba, Eiji,Oku, Akira
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p. 2771 - 2776
(2007/10/02)
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- Ru(bpy)32+ SENSITIZED PHOTOOXIDATION REACTION OF cis-STILBENES NOVEL PRODUCTS FORMATION
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Ru(bpy)32+ sensitized photooxidation of cis-stilbenes in acetonitrile gave novel cycloadducts.Products distribution changed remarkably depending on sensitizers.
- Futamura, Shigeru,Ohta, Hiroyuki,Kamiya, Yoshio
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p. 381 - 384
(2007/10/02)
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- KINETICS OF THE N OXIDATION OF SOME COMPOUNDS OF THE PYRIDINE SERIES WITH PERBENZOIC ACID IN CHLOROFORM AND AQUEOUS DIOXANE
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A comparative study of the kinetics of the N oxidation of 19 derivatives of the pyridine series with perbenzoic acid in choroform and aqueous dioxane at 20, 25, 30, and 35 deg C was made.The rate constants, the parameters of the Arrhenius equation, and the activation energies of the N oxidation of the indicated monoazines were determined.The scale of the reactivities of the derivatives of the pyridine series was calculated within the framework of the Pearson hard-soft acid-base concept.
- Lohkov, R.E.
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p. 264 - 271
(2007/10/02)
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