共查询到20条相似文献,搜索用时 15 毫秒
1.
Inack Ngi S Guilloteau V Abarbri M Thibonnet J 《The Journal of organic chemistry》2011,76(20):8347-8354
In the presence of copper(I) iodide, heteroaromatic β-iodo-α,β-unsaturated carboxylic acid systems opposed to terminal alkyne afford selectively 6-endo-dig cyclization products via a tandem coupling oxacyclization reaction. 相似文献
2.
Iodine and several of its oxides react with alkynyl alcohols in methanol to afford β-iodo-α,β-unsaturated ketones. 相似文献
3.
Keisuke Sano 《Journal of fluorine chemistry》2009,130(8):708-713
The deoxyfluorination reaction of β-diketones with N,N-diethyl-α,α-difluoro-m-methylbenzylamine (DFMBA) gave β-fluoro-α,β-unsaturated ketones in good yields. The reaction proceeded regioselectively, and only one regioisomer was obtained from the unsymmetrical 1-aryl-1,3-diketones. The reaction is applicable to diketones with a trifluoromethyl group, obtaining good yields of 3,4,4,4-tetrafluorobutenones. We used the resulting β-fluoro-α,β-unsaturated ketones for the reaction with lithium dialkyl cuprates. 相似文献
4.
The 1,3-dipolar cycloaddition reaction of 1-vinylimidazole and β-(1-imidazolyl)-α,β-unsaturated carboxylic esters with N.α-diphenylnitrone and acetonitrile oxide was carried out and compared with those of β-pyrrolidinyl- and β-phenyl-α,β-unsaturated carboxylic esters. The imidazolyl moiety bonded to olefinic double bond was suggested to have properties intermediate to pyrrolidinyl and phenyl groups. 相似文献
5.
A general method for the synthesis of β-(2-furyl)-α,β-unsaturated aldehydes is described using the Suzuki coupling reaction of furan-2-boronic acids and β-bromo-α,β-unsaturated aldehyde derivatives. 相似文献
6.
A number of α-iodo-α,β-unsaturated compounds 3 were synthesized under mild conditions via corresponding readily available arsonium salts 1 in one pot reaction. 相似文献
7.
Thivisha Rajagopal 《Tetrahedron》2010,66(45):8739-8744
E-β-Chloro-α-iodo-α,β-unsaturated esters were converted to single isomer trisubstituted olefins bearing alkyl substituents by using and alkyl-Suzuki cross coupling. The process was highly selective, and the products in all cases were isolated as single isomers. Mechanistic investigations indicated that this process transfers a hydrogen from water to the α-position of the substrate, and then an alkyl group is introduced to the β-position of the intermediate template while replacing a chloride. 相似文献
8.
The synthesis of new α,β-unsaturated furanuronic acid derivatives of α-gluco-, β-gluco- and β-manno-chloraloses via a convenient one pot procedure using the Knoevenagel-Doebner reaction approach are described. The dialdofuranose derivatives were reacted with malonic acid under Knoevenagel-Doebner reaction conditions and (E)-α,β-unsaturated furanuronic acid derivatives were obtained. 相似文献
9.
Elzbieta Lewandowska 《Tetrahedron》2006,62(20):4879-4883
The α-addition of alkyl or aryl thionucleophiles to β-nitro-α,β-unsaturated alkenoates in THF in the presence of TEA or DBU gave access to the α-thio-α,β-unsaturated alkenoates. The reaction occurred via formation of β-nitro-α-thioalkanoates and concomitant elimination of nitrous acid from the α-adducts. 相似文献
10.
A diastereomeric conjugate addition of dialkylaluminum chloride to 1-(α,β-unsaturated acyl)hydantoin provided the corresponding alkyl adduct with inducted chirality in the β-position. Treatment of 1-(α,β-unsaturated acyl)hydantoin with Gilman reagent in the presence of Lewis acid also gave the same product. In this reaction, diethylaluminum chloride was the most effective Lewis acid and the absolute configuration of the major adduct at the β-position of acyl group depended on the kinds of existing metals. 相似文献
11.
The Lewis acid-promoted reaction of β,γ-unsaturated α,α-dimethoxy esters, which are easily prepared by the acetalization of β,γ-unsaturated α-keto esters, with silyl nucleophiles is presented. By employing trimethylsilyl enolate and allyltrimethylsilane as nucleophiles, the BF3-promoted reactions of a series of β,γ-unsaturated α,α-dimethoxy esters bearing aromatic and aliphatic substituents proceeded at the γ-position in an SN2′ manner to furnish γ-substituted α,β-unsaturated α-methoxy esters in good yields with high regioselectivity. In contrast, the reaction using trimethylsilyl cyanide predominantly occurred at the α-position, and the reaction of silyl hydride resulted in a mixture of α- and γ-regioisomers in favor of the γ-substitution products. 相似文献
12.
Pranjal BezbaruahJunali Gogoi Kommuri S. RaoPranjal Gogoi Romesh C. Boruah 《Tetrahedron letters》2012,53(33):4389-4392
An efficient microwave promoted one-pot synthesis of steroidal and non-steroidal isothiazole derivatives from corresponding β-bromo-α,β-unsaturated aldehydes has been described using a sodium thiocyanate-urea system. The β-bromo-α,β-unsaturated aldehydes derivatives are efficiently synthesized from corresponding cyclic ketones using Vilsmeir formylation reaction. The synthetic protocol is also applied for the synthesis of antifungal brassilexin. 相似文献
13.
Tatsuo Ishiyama Jun Takagi Akihiro Kamon Norio Miyaura 《Journal of organometallic chemistry》2003,687(2):284-290
Cross-coupling reaction of bis(pinacolato)diboron with β-(trifluoromethanesulfonyloxy)-α,β-unsaturated carbonyl compounds was carried out in the presence of PdCl2(PPh3)2-2PPh3 (3 mol%) and KOPh in toluene or K2CO3 in dioxane for the synthesis of cyclic and acyclic β-boryl-α,β-unsaturated esters, amides, and ketones in high yields. The vinylboronates thus obtained readily participated in carboncarbon bond formation such as cross-coupling with vinyl triflates and 1,4-addition to α,β-unsaturated ketones. 相似文献
14.
Choji Kashima Katsumi Takahashi Kiyoshi Fukusaka Akira Hosomi 《Journal of heterocyclic chemistry》1998,35(3):503-511
The conjugate additions of N-(α,β-unsaturated)acylpyrazoles were carried out by the treatment with Grignard reagents in the presence of cuprous halides. The reaction of 2-(α,β-unsaturated)acyl-3-phenyl-l-menthopyrazoles 3a-h occurred in higher chemical yields and with asymmetric inductions on β-position, where the addition of magnesium bromide as a Lewis acid influenced to the yields and the diastereoselectivities. In the case of α-methylated 2-(α,β-unsaturated)acyl-3-phenyl-l-menthopyrazoles 3i-n , the excellent asymmetric induction on the α-position was also observed through the diastereofacial protonation. 相似文献
15.
Ferrocene reacts with β-ketophosphonates and β-ketosulfones (or acetals of formylphosphonates and sulfones) in the presence of a strong acid (triflic or methanesulfonic) to afford β-ferrocenyl-α,β-unsaturated phosphonates and β-ferrocenyl-α,β-unsaturated sulfones in good yield. The (E)-stereochemistry of these compounds was confirmed by spectral and analytical data, as well as by X-ray diffraction. 相似文献
16.
A Pd-catalyzed protocol has been developed for the synthesis of fused steroidal and non-steroidal pyrimidines from β-halo-α,β-unsaturated aldehydes under microwave irradiation. The β-halo-α,β-unsaturated aldehydes are synthesized from corresponding ketones using Vilsmeier formylation reaction. This synthetic protocol is utilized to synthesize some more novel steroidal pyrimidine derivatives and are currently being evaluated for their biological activities. 相似文献
17.
2-Acetonyl or 2-phenacyl-l,2-dihydropyrimidines (5) were obtained by the reaction of β-sulfinyl or β-sulfenyl-α,β-unsaturated ketones (2 or 3) with diimines (1). The formation of 1,2-dihydropyrimidines (5) can be explained in terms of substitution reaction and subsequent Michael addition of amino group of diimines (1). 相似文献
18.
Minoru Ozeki Honoka Egawa Toshiki Takano Hideki Mizutani Narumi Yasuda Kenji Arimitsu Tetsuya Kajimoto Shinzo Hosoi Hiroki Iwasaki Naoto Kojima Manabu Node Masayuki Yamashita 《Tetrahedron》2017,73(15):2014-2021
A practical method for the synthesis of chiral β2,3-amino esters having various substituents was developed, which is characterized by an asymmetric Michael addition reaction of a chiral lithium amide with trisubstituted (E)-α,β-unsaturated esters. We found that a highly face-selective protonation occurred by the quick addition of water to the enolate intermediate derived from the Michael addition reaction to afford N-protected β2,3-amino esters in moderate to excellent yields. This finding was made possible by the facile preparation of geometrically pure trisubstituted (E)-α,β-unsaturated esters, which was established recently by our group. The subsequent deprotection of the amino group in the Michael adduct by using N-iodosuccinimide (NIS) efficiently provided β2,3-amino esters having various substituents. 相似文献
19.
《Tetrahedron: Asymmetry》2014,25(8):650-657
The first organocatalytic asymmetric aldol reaction of isocyanoesters with various β,γ-unsaturated α-ketoesters has been described. Using cinchona alkaloid-derived bifunctional thiourea as the catalyst, chiral β-hydroxy-α-amino acid derivatives can be obtained in excellent yields and enantioselectivities (up to 95% yield and 92% ee) after acidic hydrolysis. This protocol provides a straightforward method to access multiple substituted β-hydroxy-α-amino acid derivatives with high enantiomeric purity. 相似文献
20.
Homologation of α-hydroxy acids to α-unsubstituted β-hydroxy carboxamides via Arndt-Eistert reaction
Here we studied the homologation of leucic and phenyl lactic acid via Wolff-rearrangement of their diazoketones to the corresponding β-hydroxy acids. This reaction requires distinct conditions to that of their amino acid analogues. The choice of the Oα-substituent can selectively direct the reaction to α-unsubstituted β-hydroxy carboxamides or (E)-α,β-unsaturated carboxamides and offers a new route from α-hydroxy acids to such compounds. 相似文献