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排序方式: 共有187条查询结果,搜索用时 31 毫秒
1.
Titanium tetrachloride promoted reaction of silyl ketene acetals with epoxides, followed by acidic work-up, affords butanolides in moderate/good yields. With epihalohydrins the reaction is regioselective and occurs at the less substituted end of the epoxide; the γ-haloalkyl-γ-butanolides thus obtained can be further transformed into various products. 相似文献
2.
《Tetrahedron letters》2004,45(40):7495-7498
A mild and efficient synthesis of β-amino alcohols by aminolysis of epoxides promoted by indium tribromide is described. The methodology is regio- and chemoselective and works well with independence of the epoxide or the aromatic amine used. In addition, the reaction can be carried out in a wide variety of undried solvents under air. 相似文献
3.
N-Alkoxycarbonyl- and N-carboxamido-oxaziridines are shown to react with aromatic alkenes to give epoxide, aziridine or hydro-oxidation products, in ratios depending on the oxaziridine structure. Chiral oxaziridines can effect epoxidation and hydro-oxidation with promising levels of asymmetric induction. 相似文献
4.
A chiral base route to a range of highly functionalised amino cyclopentenes has been developed. The key asymmetric step involved the chiral lithium amide base-mediated rearrangement of a protected trans-4-hydroxy cyclopentene oxide to give an allylic alcohol (88% ee). Subsequent Overman rearrangement gave a protected trans-1,2-aminocyclopentenol whereas Mitsunobu substitution with BocNHNs gave a protected cis-amino cyclopentenol. Both are proven intermediates for natural product synthesis. The protected cis-aminocyclopentenol was transformed in a few steps into a precursor of the cyclopentene core of nucleoside Q, a natural product whose deficiency in animals is related to tumour growth. 相似文献
5.
Rosario Torregrosa 《Tetrahedron》2007,63(2):469-473
The reaction of different epoxides with commercially available imidazole at 60 °C leads to the formation of the corresponding 1-(β-hydroxyalkyl)imidazoles in a regioselective manner. When the reaction is applied to a chiral epoxide [(R)-styrene oxide], the expected chiral alcohol is isolated with the same enantiomeric excess. The use of benzimidazole as the heterocyclic component in the same process also allows the simple preparation of the corresponding 1-(β-hydroxyalkyl)benzimidazoles. 相似文献
6.
Kazem D. Safa Mohammad Shahrivar Shahin Tofangdarzadeh Akbar Hassanpour 《Tetrahedron》2007,63(15):3189-3194
Metalation of (HSiMe2)3CH with lithium diisopropylamide (LDA) in THF gives (HSiMe2)3CLi, which reacts with ethylene oxide, propylene oxide, 1,2-epoxy butane, 1,2-epoxy pentane, 1,2-epoxy hexane, and epichlorohydrin to give the corresponding 1-oxa-2-silacyclopentane derivatives. Then, glycidylmethacrylate (GM) random copolymers with styrene (St) (in a 1:1 and 1:3 mol ratio) were synthesized by solution free radical polymerization at 70(±1) °C using α,α′-azobis(isobutyronitrile) (AIBN) as an initiator. Both types of copolymers were treated with (HSiMe2)3CLi to give new modified copolymers. The reaction of (HSiMe2)3CLi with epoxides on the side chains of the copolymers does not lead to intramolecular nucleophilic attack contrary to simple epoxides. All the products have been characterized by spectroscopic techniques. 相似文献
7.
Aryane A. Marciniak Katie J. Lamb Leonardo P. Ozorio Claudio J.A. Mota Michael North 《Current Opinion in Green and Sustainable Chemistry》2020
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8.
Hossein?EshghiEmail author Sayyed Faramarz?Tayyari Esmaiel?Sanchuli 《Monatshefte für Chemie / Chemical Monthly》2004,135(9):1101-1111
Summary. The regioselective ring opening of epoxides using elemental iodine and bromine in the presence of o-phenylenediamine as a new catalyst affords vicinal iodo alcohols and bromo alcohols in high yields. The major advantages of this method are versatility, high regioselectivity, a cheap and commercially available catalyst, mild and neutral reaction conditions, and short reaction times. Fourier transform Raman spectroscopy was used to study the reaction of iodine with o-phenylenediamine. The results indicate that the complex [(Diamine)I]+·I5– is formed, and we suggest that the major nucleophile is the pentaiodide ion. This bulky nucleophile has a fundamental role in the high regioselectivity observed attacking the less sterically hindered epoxide carbon. 相似文献
9.
Irina V. Il'ina Konstantin P. Volcho Dina V. Korchagina Vladimir A. Barkhash Nariman F. Salakhutdinov 《Helvetica chimica acta》2007,90(2):353-368
The reactivity of allyl alcohols of the pinane series and of their epoxides in the presence of montmorillonite clay in intra‐ and intermolecular reactions was studied. Mutual transformations of (+)‐trans‐pinocarveol ((+)‐ 2 ) and (?)‐myrtenol ((?)‐ 3a ) were major reactions of these compounds on askanite–bentonite clay (Schemes 1 and 2). However, the two reactions gave different isomerization products, indicating that the reactivity of the starting alcohol (+)‐ 2 or (?)‐ 3a was different from that of the same compound (+)‐ 2 or (?)‐ 3 formed in the course of the reactions. (?)‐cis‐ and (+)‐trans‐Verbenol ((?)‐ 16 and (+)‐ 12 , resp.), as well as (?)‐cis‐verbenol epoxide ((?)‐ 20 ) reacted with both aliphatic and aromatic aldehydes on askanite–bentonite clay giving various heterocyclic compounds (Schemes 4, 5 and 7); the reaction path depended on the structure of both the terpenoid and the aldehyde. 相似文献
10.
A simple, efficient, and new method has been developed for the synthesis of thiiranes from epoxides through a one-pot reaction of epoxides with diethyl phosphite in the presence of ammonium acetate or ammonium hydrogen carbonate/sulfur/ and acidic alumina under solvent-free conditions using microwave irradiation. 相似文献