20248-57-1Relevant academic research and scientific papers
Method used for direct synthesis of epoxy compounds from alcohol
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Paragraph 0244-0251, (2019/10/08)
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.
Practical and highly selective sulfur ylide-mediated asymmetric epoxidations and aziridinations using a cheap and readily available chiral sulfide: Extensive studies to map out scope, limitations, and rationalization of diastereo- and enantioselectivities
Illa, Ona,Namutebi, Mariam,Saha, Chandreyee,Ostovar, Mehrnoosh,Chen, C. Chun,Haddow, Mairi F.,Nocquet-Thibault, Sophie,Lusi, Matteo,McGarrigle, Eoghan M.,Aggarwal, Varinder K.
supporting information, p. 11951 - 11966 (2013/09/02)
The chiral sulfide, isothiocineole, has been synthesized in one step from elemental sulfur, γ-terpinene, and limonene in 61% yield. A mechanism involving radical intermediates for this reaction is proposed based on experimental evidence. The application of isothiocineole to the asymmetric epoxidation of aldehydes and the aziridination of imines is described. Excellent enantioselectivities and diastereoselectivities have been obtained over a wide range of aromatic, aliphatic, and α,β-unsaturated aldehydes using simple protocols. In aziridinations, excellent enantioselectivities and good diastereoselectivities were obtained for a wide range of imines. Mechanistic models have been put forward to rationalize the high selectivities observed, which should enable the sulfide to be used with confidence in synthesis. In epoxidations, the degree of reversibility in betaine formation dominates both the diastereoselectivity and the enantioselectivity. Appropriate tuning of reaction conditions based on understanding the reaction mechanism enables high selectivities to be obtained in most cases. In aziridinations, betaine formation is nonreversible with semistabilized ylides and diastereoselectivities are determined in the betaine forming step and are more variable as a result.
Rhodium-catalyzed synthesis of terminal alkenes
Paquet, Valerie,Lebel, Helene
, p. 1901 - 1905 (2007/10/03)
Terminal alkenes have been efficiently prepared via a rhodium-catalyzed olefination procedure using Wilkinson's catalyst in the presence of triphenylphosphine, 2-propanol and trimethylsilyldiazomethane. Optimized reaction conditions are described for aldehydes and ketones, as well as alternative work up procedures. Georg Thieme Verlag Stuttgart.
New mechanistic aspects on the catalytic transformation of vinylthiiranes to mono and disubstituted 3,6-dihydro-1,2-dithiins by tungsten pentacarbonyl monoacetonitrile
Lupton, David W,Taylor, Dennis K
, p. 4517 - 4527 (2007/10/03)
Various alkyl and aryl mono- and disubstituted 3,6-dihydro-1,2-dithiins have been synthesised from their corresponding vinylthiiranes exploiting Adams' tungsten pentacarbonyl monoacetonitrile catalytic transformation. New conclusions pertaining to the rate determining step, the sensitivity of the process to precursor sterics and electronics, and the nature of various reaction intermediates are highlighted.
Methylenation of aldehydes: Transition metal catalyzed formation of salt-free phosphorus ylides
Lebel, Heandleandne,Paquet, Valeandrie,Proulx, Caroline
, p. 2887 - 2890 (2007/10/03)
A variety of terminal alkenes are produced in excellent yields by the rhodium(I)-catalyzed methylenation of aldehydes using TMSCHN2 and PPh3 [Eq. (1)]. These mild reaction conditions allowed the conversion of enolizable substrates and the chemoselective methylenation of aldehydes over ketones. TMS = trimethylsilyl.
Process for the preparation of an oxirane, azirdine or cyclopropane
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, (2008/06/13)
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.
Indium-mediated reaction of 1,3-dichloro- and 1,3-dibromopropenes with carbonyl compounds. Generation of novel 3,3-diindiopropene
Araki, Shuki,Hirashita, Tsunebisa,Shimizu, Hidetaka,Yamamura, Hatsuo,Kawai, Masao,Butsugan, Yasuo
, p. 8417 - 8420 (2007/10/03)
Indium-mediated reaction of 1,3-dichloropropene with aldehyde gave syn-chlorohydrin predominantly. A similar reaction of 1,3-dibromopropene gave vinyloxirane and homoallyl alcohol; the former is formed from γ-bromoallylindium via the corresponding bromohydrin, and the latter is considered to be derived from a unique allylic diindium reagent, 3,3-diindiopropene.
A Novel Catalytic Cycle for the Synthesis of Epoxides Using Sulfur Ylides
Aggarwal, Varinder K.,Abdel-Rahman, Hesham,Fan, Li,Jones, Ray V. H.,Standen, Mike C. H.
, p. 1024 - 1030 (2007/10/03)
A novel, neutral catalytic cycle for the synthesis of epoxides from carbonyl compounds and diazo compounds using catalytic quantities of transition metal salts and sulfides has been developed.In this catalytic cycle, the diazo compounds is decomposed by the transition metal salt to give a metallocarbene, and this is picked up to the sulfide to give a sulfur ylide, which then reacts with the aldehyde to give an epoxide and returns the sulfide back into the catalytic cycle.To obtain good yields of epoxides it is necessary to maintain a low concentration of the diazo compound (by slow addition), otherwise dimerisation of the diazo compound is the dominant reaction.Factors affecting the outcome of the reaction were studied.The reactions are relatively insensitive to solvent, but are sensitive to the structure of the sulfide, the metal salt and the concentration.Unhindered sulfides give good yields of epoxides with any metal salt, but with hindered sufides higher yields are obtained with Cu(acac)2 than with Rh2(OAc)4.The yields of epoxides are sensitive to sulfide concentration especially when using substoichiometric amounts of sulfides.Higher concentration leads to faster rates of formation and subsequent reaction of the sulfur ylides, and consequently to higher yields.This novel catalytic cycle has also been applied to base-sensitive aldehydes.We found that our new catalytic cycle for epoxidation gives much improved yields of epoxides compared to those obtained by traditional sulfur ylide chemistry and is tolerant to a wide variety of sensitive functional groups.Ketones also participate in the catalytic cycle, although they give reduced yields of epoxides compared to aldehydes and require a slightly elevated temperature. - Keywords: catalysis; diazo compounds; epoxidations; sulfur ylides; synthetic methods
Regio- and enantio-selective catalytic epoxidation of conjugated dienes
Rasmussen, Kaare G.,Thomsen, Dorte S.,Joergensen, Karl Anker
, p. 2009 - 2018 (2007/10/02)
The regio-and enantio-selective catalytic epoxidation of conjugated aliphatic dienes have been studied using a variety of achiral and chiral manganese salen complexes and sodum hypochlorite or iodosylbenzene as the terminal oxidant.The catalysts show a preference for the less substituted alkene in most of the dienes studied, and in some cases a regioselectivity of 100percent is found.The regioselectivity is dependent on the terminal oxidant applied.The enantiomeric excess (ee) obtained varies for the different conjugated dienes and the ee is generally highest for internal alkenes, where an ee of up to 71percent is observed, whereas 48percent is the highest observed ee for the less substituted alkenes.The ee is also dependent on the terminal oxidant applied.The regio- and enantio-selectivity have also been studied for different 1-(para-substituted phenyl)buta-1,3-dienes, but no regio- and enantio-selectivity dependence on the different subsituents are observed.A competitive epoxidation experiment with styrene and 1-phenylbuta-1,3-diene shows that the latter is the most reactive and the difference in reactivity is discussed on the basis of frontier orbitals of the two systems.The electronic structure of the oxo-manganese salen intermadiate is investigated using INDO/1 calculations and it is found that the triplet state is the most stable state of the intermediate.Based on the electronic structure of the oxo-maganese salen intermediate a mechanism of the oxygen transfer step to the conjugated diene is proposed.
Carbonyl Allylation by Vinyl Epoxides with SnCl2-TBA or SnCl2-LiI: Application to the Diastereoselective Synthesis of 1,3-Diols
Masuyama, Yoshiro,Nakata, Jun,Kurusu, Yasuhiko
, p. 2598 - 2599 (2007/10/02)
Vinyl epoxides reacted with aldehydes in the presence of stannous chloride-tetrabutylammonium bromide or stannous chloride-lithium iodide to produce 2-vinyl-1,3-diols regio- and diastereoselectively.
