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1.
A variety of carboxylic acids have been screened for mediating the allylation of aldehydes with allytributyltin in different solvents. A novel, general, and practical method of allylation of aldehydes promoted by carboxylic acids under mild reaction conditions has been developed. Among them, p-nitrobenzoic acid afforded high to quantitative yields of the homoallylic alcohol products, and can be easily recovered after workup by aqueous HCl. Glyoxylic acid self-catalyzed the allylation without adding any other promoter or catalyst to give the corresponding allylation product in good yield. The regioselectivity of the crotylation of aldehydes is tunable by controlling the acidity of the carboxylic acids. The crotylation of aldehydes produced the alpha-adduct as major products in moderate to good yields with CF(3)CO(2)H as a promoter. A possible mechanism for the allylation is also discussed. 相似文献
2.
J.S. Yadav V. Sunitha B.V. Subba Reddy P.P. Das E. Gyanchander 《Tetrahedron letters》2008,49(5):855-857
A new method for the stereoselective synthesis of trans-2,6-disubstituted 3,6-dihydro-2H-pyrans with a variety of substitution patterns is described, involving Lewis acid induced tandem allylation or cyanation of δ-hydroxy-α,β-unsaturated aldehydes to produce dihydropyrans in good yields and with trans-selectivity. This method is very useful for the synthesis of trans-2,6-disubstituted dihydropyran ring-containing natural products such as laulimalide, scytophycin C and many others. 相似文献
3.
Copper was found to be able to promote the SnC12-mediated carbonyl allylation reactions in water, giving the corresponding homoallylic alcohol products in very high yields. Detailed studies showed that the reaction could be applied to a variety of carbonyl compounds including those with hydroxyl, amino and nitro groups. It was also found that this reaction showed good regioselectivities for some substrates. Furthermore, carefully controled experiments and in situ NMR measurements provided important insights into the mechanism of the newly developed reaction. 相似文献
4.
Conjugate allylation reactions of alpha,beta-unsaturated N-acylpyrroles using allylboronic ester are catalyzed by a palladium complex that is ligated by a bidentate N-heterocyclic carbene. A variety of functional groups are tolerated, and substrates functionalized with electron-withdrawing groups react to afford the highest yields of products. Regioselectivity for 1,4-allylation over 1,2-allylation is demonstrated, and mechanistic experiments are consistent with formation of nucleophilic allylpalladium intermediates. 相似文献
5.
《Comptes Rendus Chimie》2009,12(8):916-921
The activity of various metallic triflates and triflimidates in the Friedel–Crafts allylation of activated aromatic rings was examined. Zinc bis(trifluoromethylsulfonyl)amide was proved to be a good catalyst in the model reaction with anisole and prenyl acetate. The Friedel–Crafts allylation reaction of various aryl derivatives with allyl acetates was efficiently catalysed under mild conditions, using 3 mol% of Zn(NTf2)2 as the catalyst, without solvent, at 100 °C. The desired ortho and para mono-allylated products were selectively obtained in good yields. The para isomer was always favoured. 相似文献
6.
Juliano C.R. Freitas Túlio R. Couto Antônio A.S. Paulino João R. de Freitas Filho Ivani Malvestiti Roberta A. Oliveira Paulo H. Menezes 《Tetrahedron》2012,68(41):8645-8654
Catalytic amounts of tellurium(IV) tetrachloride were used to promote the O-glycosylation of 3,4,6-tri-O-acetyl-d-glucal to give the corresponding 2,3-unsaturated-O-glycosides. With simple alcohols, the desired compounds were obtained in good yields and excellent anomeric selectivity in a short reaction time using only 2 mol % of the catalyst. The application of the method in the synthesis of a small set of glycopyranosides with rigid or flexible linkers gave the corresponding α anomers as products in good yields. Further applications of some of the synthesized compounds in allylation reaction of aldehydes gave the corresponding homoallylic alcohols in good yields. 相似文献
7.
The allylation of aromatic amines with alkynes proceeded smoothly in the presence of catalytic amounts of Pd(PPh(3))(4) and benzoic acid. The allylation products were obtained in high yields in a regio- and stereoselective manner. The effect of various groups on the nitrogen atom of anilines was studied. Regardless of the substituent (electron withdrawing or electron donating) on the aromatic ring, the reaction proceeded well. Various functionalities, including -CH(3), -OMe, -Cl, -CN, -COOMe, -NO(2) and -COCH(3) were tolerated under the reaction conditions. Similarly, the allylation of alpha-aryl aldehydes proceeded well with the same level of regio- and stereoselectivity as the allylation of aromatic amines. This reaction provides the second example of the transition metal catalyzed direct alpha-allylation of aldehydes. 相似文献
8.
Mandar P. Surpur 《Tetrahedron letters》2009,50(6):719-722
Mg/Al hydrotalcite, a heterogeneous base catalyst, was found to be highly effective for the synthesis of 2-aminochromenes via a multicomponent reaction of aromatic aldehydes, malononitriles and 1-naphthol under microwaves. The reaction is rapid, clean and gives the products in high yields. The catalyst is reusable; however, there was reduction in the yield of the product. 相似文献
9.
Silver‐Catalyzed Decarboxylative Allylation of Difluoroarylacetic Acids with Allyl Sulfones in Water
A practical silver‐catalyzed decarboxylative allylation of α,α‐difluoroarylacetic acids with allyl sulfones is described, which provides a variety of β,β‐difluorinated alkenes in good yields. Notably, the reaction proceeds smoothly in water with good functional group tolerance. The practicality and synthetic value of this process was demonstrated by scaled‐up experiment and elaboration of the products via reduction or Heck reaction. Primary mechanism investigations suggest that a radical process might be involved. 相似文献
10.
Zhifang Li 《Journal of organometallic chemistry》2008,693(25):3771-3779
Allyl and allenyl groups have been introduced into silicon systems by the allylation and allenylation of chlorosilanes using allyl bromide or propargyl bromide with indium. The allylation of chlorosilanes afforded a variety of aryl, aralkyl, and alkenyl substituted allylsilanes. By applying this method, the reactions of 1-bromo-3-methylbut-2-ene, 3-bromo-2-methylprop-1-ene and 3-bromobut-1-ene with chlorosilanes also proceed smoothly to give regioselectively allylic rearrangement products in good yields. Mediated by indium, dichlorosilanes (R2SiCl2) and trichlorosilanes (RSiCl3) can either afford monoallylated silanes or diallylated silanes depending on the amount of allyl bromide and indium used. 相似文献
11.
Palladium(0)-catalyzed deconjugative allylation of alkenylidenemalonates and alkylidenemalonates was achieved for the first time. Reactions of dimethyl 2-((E)-but-2-enylidene)malonate with various allylic acetates using LHMDS as a base in DMF in the presence of Pd(2)dba(3) (2.5 mol %) and PPh(3) (10 mol %) proceeded at room temperature to give the corresponding alpha-allylation products in good yields in a regio- and stereoselective manner. This reaction can also be used for allylation of dimethyl ethylidenemalonate or dimethyl 2-((E)-pent-2-enylidene)malonate and give the desired alpha-allylation products in good yields. 相似文献
12.
R.V.N.S. MuraliS. Chandrasekhar 《Tetrahedron letters》2012,53(27):3467-3470
Highly diastereocontrolled synthesis of alkaloids, (−)-241D and (−)-isosolenopsin was achieved in 7.7% and 5.3% yields, respectively, using a Barbier-type allylation of a chiral imine and d-proline catalyzed aldol addition reaction of a β-amino aldehyde with acetone as the key steps. The synthesis involves a nine-step sequence using (S)-valinate imine in a Barbier-type allylation for the first time. 相似文献
13.
1,1-Dicyano-2-aryl-3-benzoylcyclopropanes in acetonitrile in the presence of triethylamine underwent cyclodimerization reaction to afford the novel polyfunctionalized 1a,1b,2,5-tetrahydro-1H-5a-aza-cyclopropa[a]indenes in moderate yields. These polycyclic compounds can be more conveniently synthesized by the one-pot domino reaction of N-phenacylpyridinium bromides with arylidene malononitriles. 相似文献
14.
Kui Wu Lushun Wang Sonivette Coln‐Rodríguez Gerd‐Uwe Flechsig Ting Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1788-1792
The development of visible‐light‐mediated allylation of unactivated sp3 C?H bonds is reported. The remote allylation was directed by the amidyl radical, which was generated by photocatalytic fragmentation of a pre‐functionalized amide precursor. Both aromatic and aliphatic amide derivatives could successfully deliver the remote C?H allylation products in good yields. A variety of electron deficient allyl sulfone systems could be used as δ‐carbon radical acceptor. 相似文献
15.
Chaitanya Ittamalla Saikrishna Chintha Dr. Nagaraju Medishetti Dr. Jagadeesh Babu Nanubolu Dr. Krishnaiah Atmakur 《European journal of organic chemistry》2023,26(22):e202300357
Synthesis of title compounds were accomplished by a reaction of vinyl malononitriles and arylidene pyrazolones catalyzed by base. This protocol proceeds via Michael addition followed by intramolecular cyclization leading to the formation of two new C−C bonds. Further the same reaction was also conducted with α,α-dicyano olefins and vinyl malononitriles to furnish 1,6-dihydro biphenyl compounds. Simple reaction conditions, high yields and compatibility are the advantages of this protocol. 相似文献
16.
17.
Christian A. Malapit Donald R. Caldwell Irungu K. Luvaga Dr. Jonathan T. Reeves Dr. Ivan Volchkov Dr. Nina C. Gonnella Dr. Zhengxu S. Han Dr. Carl A. Busacca Prof. Dr. Amy R. Howell Dr. Chris H. Senanayake 《Angewandte Chemie (International ed. in English)》2017,56(24):6999-7002
β-Ketonitriles bearing a quaternary carbon at the 2-position were prepared through Rh-catalyzed addition of aryl boronic acids to 2,2-disubstituted malononitriles. In contrast to the previously described transnitrilative cyanation of aryl boronic acids with dialkylmalononitriles, the present reaction avoids retro-Thorpe collapse of the intermediate addition product through the use of a milder base. The reaction was amenable to a variety of aryl boronic acids and disubstituted malononitriles, providing a diverse array of β-ketonitriles. The products could be further derivatized to valuable chiral α,α-disubstituted-β-aminonitriles through addition reactions to the corresponding N-tert-butanesulfinyl imines. 相似文献
18.
The heterogeneous carbonyl allylation of aldehydes and ketones with allylic chlorides was achieved in DMF using SnCl2 as reducing agent at 25-40 °C in the presence of a 3-(2-aminoethylamino)propyl-functionalized MCM-41-immobilized palladium(II) complex [MCM-41-2N-Pd(II)], yielding a variety of homoallylic alcohols in good to high yields. This heterogeneous palladium catalyst exhibited higher activity than (N-propylethylenediamine)PdCl2 and can be recovered and recycled by a simple filtration of the reaction solution and used for at least 5 consecutive trials without any decreases in activity. 相似文献
19.
A variety of functionalized 6-(trifluoromethyl)-6H-dibenzo[b,d]pyrans were easily synthesized in good yields under mild conditions by a domino reaction of 3-nitro-2-(trifluoromethyl)-2H-chromenes with 2-(1-phenylethylidene)- and 2-(1-phenylpropylidene)malononitriles. In the latter case, intermediate 7-amino-10-methyl-10-nitro-9-phenyl-6-(trifluoromethyl)-10,10a-dihydro-6H-benzo[c]chromene-8-carbonitriles were isolated as a result of a rare [1,5] sigmatropic shift of the nitro group. 相似文献
20.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(24):7103-7106
β‐Ketonitriles bearing a quaternary carbon at the 2‐position were prepared through Rh‐catalyzed addition of aryl boronic acids to 2,2‐disubstituted malononitriles. In contrast to the previously described transnitrilative cyanation of aryl boronic acids with dialkylmalononitriles, the present reaction avoids retro‐Thorpe collapse of the intermediate addition product through the use of a milder base. The reaction was amenable to a variety of aryl boronic acids and disubstituted malononitriles, providing a diverse array of β‐ketonitriles. The products could be further derivatized to valuable chiral α,α‐disubstituted‐β‐aminonitriles through addition reactions to the corresponding N ‐tert ‐butanesulfinyl imines. 相似文献