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51.
1,4-Disubstituted 1,2,3-triazoles are obtained in excellent yields via a three-component coupling of secondary alcohols, alkynes and trimethylsilyl azide (TMSN3). This one-pot reaction occurs through in situ generation of an azide from the alcohol and TMSN3, followed by 1,3-dipolar cycloaddition of the terminal alkyne to afford the corresponding disubstituted triazoles. 相似文献
52.
Anthony J. PearsonJin Bum Kim 《Tetrahedron letters》2003,44(46):8525-8527
A new approach to the synthesis of substituted biaryls, via Diels-Alder reaction between cyclopentadienones and arylacetylenes, is described. 相似文献
53.
Combinatorial library of isoxazoles was prepared by 1,3-dipolar cycloaddition on solid support. p-Cyano derivatives showed nematic and/or smectic A phases. A bilayer smectic phase for 2h is proposed by the combination of molecular mechanics calculation and X-ray diffraction experiment. 相似文献
54.
Dihydrothiinone 9a undergoes photocycloaddition regioselectively to all three C?C bonds of penta‐1,2,4‐triene ( 10 ), the relative stabilities of the biradical intermediates determining the product distribution. In contrast, cyclohexenone 9b and dihydropyranone 9c afford more complex mixtures of bicyclo[4.2.0]octanones, which also turn out to be less stable on chromatographic workup, reflecting the higher strain due to the shorter bond lengths (C? O and C? C vs. C? S) in the six‐membered rings, respectively. 相似文献
55.
D. V. Tsyganov A. P. Yakubov L. D. Konyushkin S. I. Firgang V. V. Semenov 《Russian Chemical Bulletin》2007,56(12):2460-2465
A series of analogs of the natural mitostatic agent combretastatin were synthesized by the reaction of nitrile oxides with
natural allylbenzenes, such as myristicin, apiol, and dillapiol. The 1,3-dipolar cycloaddition reactions in allylic systems
proceed regiospecifically. The reactions with trans isomers of propenylbenzenes, viz., isomyristicin, isoapiol, and isodillapiol, as dipolarophiles produce regioisomers.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2375–2380, December, 2007. 相似文献
56.
[2+2] Carbonylative cycloaddition of chiral imines to various allyl halides, under CO pressure, in the presence of Et3N, a catalytic amount of Pd(OAc)2 and PPh3 as ligand, are carried out. Separable diastereomeric mixtures of chiral alkenyl-β-lactams are isolated with good yields and high trans diastereoselections. Absolute configurations are assigned by X-ray measurements and 1H NMR spectroscopy. 相似文献
57.
本文报道用环加成-芳构化串连反应制备多取代芳香族化合物的方法。将1-氯-2-卤-3-苯硒基-1,3-丁二烯(5)与丁炔二酸二甲酯进行Diels-Alder反应时,能直接生成多取代的芳香族化合物4-苯硒基-5-卤代邻苯二甲酸二甲酯(4)。若用2-卤素-3-苯硒基-1,3-丁二烯(1)与丁炔二酸二甲酯进行Diels-Alder反应,只得到正常的加成产物4-苯硒基-5-卤素-1,4-环己二烯-1,2-二甲酸二甲酯(3),需再用DDQ处理,才得到多取代芳香族化合物(4)。 相似文献
58.
Bis- as well as tris-tetrahydropyranone ring systems were obtained via multiple tandem cyclization-1,3-dipolar cycloaddition reactions of α-diazo ketones with ketone as well as aldehyde functional groups in a chemoselective manner. 相似文献
59.
Jason D. Katz 《Tetrahedron》2004,60(43):9559-9568
A highly functionalized 4,5-dihydropyrrole-2-carboxylate is assembled by alkene-enamide ring-closing metathesis. Subsequent intramolecular azomethine imine dipolar cycloaddition provides a triazacyclopenta[cd]pentalene intermediate of potential use in a total synthesis of palau'amine. 相似文献
60.
AFacileSynthesisofindolizinesby1,3-DipolarCycloadditionofPyridiniumandRelatedHeteroaromaticYlideswithAlkenesinthePresenceofTP... 相似文献