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1.
An efficient synthesis of functionalized 4H-chromenes by the tandem reaction of b,g-unsaturated aketoesters with 2-naphthols,1-naphthols,and 1,3-dihydroxynaphthalenes has been accomplished with high selectivity and excellent yields in the presence of a catalytic amount of bismuth triflate [Bi(OTf)3,5 mol%] under mild conditions.The functionalized 4H-chromene synthesis and our previous 2Hchromene hemiacetal synthesis could complement each other to enrich reaction diversity. 相似文献
2.
《Tetrahedron: Asymmetry》1999,10(4):713-719
Several chiral guanidines were evaluated as catalysts for the Michael reaction of glycine derivatives 7 with acrylic esters 8. The best result (30.4% ee) was obtained when 7b was reacted with 8b under the catalysis of guanidine 1 in THF. 相似文献
3.
An efficient and selective approach for the synthesis of functionalized pyranocoumarins has been developed via a gold(III)-catalyzed tandem conjugate addition/annulation reaction of 4-hydroxycoumarins with α,β-unsaturated ketones. 相似文献
4.
Hui-Jing Li ;Dong-Hui Luo ;Qin-Xi Wu ;Chun-Yang Dai ;Zhi-Lun Shen ;Yan-Chao Wu 《中国化学快报》2014,25(9):1235-1239
An efficient synthesis of functionalized 4H-chromenes by the tandem reaction of β,γ-unsaturated α- ketoesters with 2-naphthols, 1 -naphthols, and 1,3-dihydroxynaphthalenes has been accomplished with high selectivity and excellent yields in the presence of a catalytic amount of bismuth triflate [Bi(OTf)3, 5 mol%] under mild conditions. The functionalized 4H-chromene synthesis and our previous 2H- chromene hemiacetal synthesis could complement each other to enrich reaction diversity. 相似文献
5.
A facile total synthesis of marine natural product (±)-spiniferin-1 has been accomplished in eight steps with 28.9% overall yield, involving a rearrangement reaction initiated by polyfluoroalkanosulfonyl fluoride to construct the 1,6-methano[10]annulene core of the natural product as a key step. 相似文献
6.
Structurally diverse functionalized 4-(1-haloalkyl)-3-nitrotetrahydrofurans were conveniently obtained in moderate to good yield and moderate to very good diastereoselectivity by an oxidative tandem process consisting of conjugate addition reaction of lithium allyloxides to nitroalkenes followed by SET oxidation of the resulting nitronates. This triggers a radical cyclization; ligand transfer from the oxidant provides the products. The influence of the counter ion of the initial alkoxide and intermediate nitronate, the solvent and additives on the outcome of the tandem process was investigated. Optimal conditions for the tandem reactions consist of using butyllithium as the base for deprotonation in DME as the solvent. Cupric halides proved to be the SET oxidants of choice in the tandem reactions. A stereochemical model for the radical cyclization and ligand transfer steps is proposed. 相似文献
7.
HE Ming PAN ZhaoXi BAI Song LI Pei ZHANG YuPing JIN LinHong HU DeYu YANG Song SONG BaoAn 《中国科学:化学(英文版)》2013,56(3):321-328
The cinchona alkaloids catalyzed the direct asymmetric Mannich reactions of 1,3-dicarbonyl compounds with acyl imines to produce novel β-amino ester derivatives containing a quinazoline moiety.The adducts were isolated with high enantiomeric excess(up to 99%). 相似文献
8.
A variety of β-hydroxyphosphonates were produced in high yields by ring opening reaction of different types of epoxides with di/trialkyl phosphite esters catalyzed by Al(OTf)3. The reactions proceeded with complete chemo- and regioselectivity to give the title compounds. This method is new, simple and efficient for the one-pot synthesis of β-hydroxyphosphonates via direct C-P bond formation. 相似文献
9.
J.S. Yadav B.V. Subba Reddy G. Madhusudhan Reddy S. Rehana Anjum 《Tetrahedron letters》2009,50(44):6029-5515
Aldehyde, alcohol, azide, and alkyne undergo smooth coupling by means of acetal formation, azidation, and a subsequent ‘click reaction’ in the presence of copper(II) triflate and copper metal in acetonitrile to furnish α-alkoxy-1,2,3-triazoles in good yields. The method provides a convenient route to prepare a wide range of triazoles in a one-pot operation via a four-component reaction. 相似文献
10.
An efficient method for the asymmetric synthesis of β-trifluoromethylated β-amino ketones via addition of ketone-derivative enolates to trifluoromethylated sulfinylimine has been developed, with good chemical yields and excellent diastereoselectivities. This practical method was also proved to be suitable for large-scale preparation. 相似文献
11.
A simple transition-metal-free protocol for the synthesis of indoles has been developed using aryne cycloaddition. The in situ-generated arynes couple with α-amino ketones through a one-step N-arylation–nucleophilic addition process under mild conditions and efficiently produce multisubstituted N-arylindoles. 相似文献
12.
An efficient rhodium-catalyzed synthesis of 2H-azirines and pyrroles has been developed. Novel rearrangement of α-oximino ketenes derived from α-diazo oxime ethers provides 2H-azirines bearing quaternary centers and allows for subsequent rearrangement to highly substituted pyrroles in excellent yields. 相似文献
13.
14.
The enantioselective Kinugasa reaction of nitrones with terminal alkynes in the presence of 20 mol % of IndaBox-Cu(OTf)2 and di-sec-butylamine (1.5 equiv) produced β-lactams with the highest level of enantiomeric excesses among the catalytic enantioselective Kinugasa reactions reported so far. 相似文献
15.
《Tetrahedron》1988,44(13):3791-3803
Trimethylsilyllithium undergoes conjugate addition to dimethylhydrazones of α,β-unsaturated ketones. The resulting metalloenamine intermediates can be alkylated, and the resulting hydrazone products cleaved to give α-substituted-β-silyl ketones. These reactions, together with a silicon-directed Baeyer-Villiger reaction, have been applied to the synthesis of brevicomin. 相似文献
16.
Enantioselective Michael addition of α-nitrophosphonates to enones for the synthesis of α-aminophosphonates is reported for the first time. The reaction proceeds in good to high yields and moderate to high selectivity in the presence of a new quinine thiourea catalyst. The quaternary nitrophosphonates were conveniently transformed to cyclic quaternary α-aminophosphonates via in situ reduction-intramolecular cyclization or Baeyer-Villiger oxidation followed by in situ reduction-intramolecular cyclization. 相似文献
17.
Hyoung Wook Moon 《Tetrahedron letters》2009,50(34):4896-485
The catalytic enantioselective conjugate addition reaction of fluorobis(phenylsulfonyl)methane to α,β-unsaturated ketones promoted by chiral bifunctional organocatalysts is described. The treatment of fluorobis(phenylsulfonyl)methane to α,β-unsaturated ketones under mild reaction conditions afforded the corresponding Michael adducts with high enantioselectivity. The conjugate addition adducts are useful for the synthesis of chiral monofluoromethylated compounds. 相似文献
18.
《Tetrahedron letters》2019,60(26):1741-1744
The first conjugate addition reaction of organocuprates to N-enoyl oxazolidinone where a N-protected γ-nitrogen atom and an α-methyl group are present into α, β-unsaturated system is described. This reaction gave anti-products in moderate yields and high diastereomeric ratios. The anti-products have two contiguous stereogenic centers, one formed by the conjugate addition reaction and the other by a diastereoselective protonation reaction. The removal of chiral oxazolidinone moiety and N-deprotection of amino group furnished chiral α, β-disubstituted γ-amino acids. 相似文献
19.
A mild and efficient enantioselective one-pot synthesis of β-sulfonyl ketones and trisubstituted tetrahydrothiophenes via introducing 1,4-dithiane-2,5-diol to the simple kinetic resolution of β-sulfonyl ketones has been described herein. The one-pot reaction sequence including kinetic resolution and cascade sulfa-Michael/Aldol reaction proceeded successively to afford corresponding sulfonyl ketones and tetrahydrothiophenes with high enantioselectivities (85%–98% ee and 84%–95% ee, respectively). 相似文献
20.
Cs_xH_(3-x)PW_(12)O_(40) heteropoly salts catalyzed quinoline synthesis via Friedl(a|¨)nder reaction
Various type of cesium partially substituted phosphotungstate,CsxH3-xPW12O40(x = 1.0,2.0 and 2.5),were synthesized and their catalytic activities were investigated in the synthesis of quinoline.It was shown that catalytic activities of these catalysts correlated to surface acidity and total number of acidic sites.Finally,a series of quinoline derivatives were synthesized with Cs2.5H0.5PW12O40 via the Friedlander reaction in high to excellent yields and the plausible mechanism was proposed.Simple experiment,catalyst reusability,short reaction time and preclusion of toxic solvent are the advantages of this method. 相似文献