共查询到20条相似文献,搜索用时 10 毫秒
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John A Soderquist Judith Martinez Yatsandra Oyola Iveliz Kock 《Tetrahedron letters》2004,45(28):5541-5543
Brown's DCME reaction was successfully performed employing B-alkyl-9-oxa-10-borabicyclo[3.3.2]decanes (1) to provide carboxylic acids (2) in good to excellent yields with complete retention of configuration. 相似文献
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Jianmin Zhang 《Tetrahedron letters》2010,51(36):4699-393
The reaction of an α-chloroglycinate ester with the dimethylaluminum acetylide derivative of phenyl propargyl ether provides the corresponding 5-vinyloxazole in 40-50% yield. 相似文献
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Adachi Y Nakagawa H Matsuo K Suzuki T Miyata N 《Chemical communications (Cambridge, England)》2008,(41):5149-5151
We synthesized hetero-Diels-Alder cycloadducts from acyl nitroso derivatives and 9,10-dimethylanthracene, to be photo-inducible HNO-releasing agents and found that introduction of conjugated nitroaromatic groups effectively enhanced the responsiveness of HNO release to UV-A irradiation; we confirmed photoinduced HNO formation by EPR and GCMS analysis. 相似文献
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Ashantai Yungai 《Tetrahedron letters》2004,45(28):5445-5448
Readily available [4 + 3]-cycloadducts derived from trapping of the Nazarov 2-oxidocyclopentenyl cation with 2,3-dimethyl-1,3-butadiene are cleaved by ozonolysis to furnish triketones. In the presence of methanolic KOH, these triones undergo tandem aldol additions to furnish centro-hydroxylated triquinacene skeletons. 相似文献
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2-Alkynylbenzaldoxime reacts with amine catalyzed by silver triflate under mild conditions, leading to 1-aminoisoquinolines in good yield. This reaction proceeds efficiently with good functional group tolerance. 相似文献
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One new route for the synthesis of amino-substituted indazol-3,5-dione via the amidation reaction of o-carboxyazobenzenes is reported. Optimization which includes effects of the solvents, molar ratio of starting materials, and dehydrating agents on this reaction has been studied. A possible reaction mechanism has been proposed on the basis of the product's structure, and the steric hindrance could be the main reason for low yield. 相似文献
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Application of the Mundy N-acyllactam rearrangement to 6 - methyl - 2 - piperidone has led to a synthesis of optically active dihydropinidine, confirming the absolute configuration of the pine alkaloid pinidine, and to a new synthesis of the fire ant toxin, Solenopsin A. 相似文献
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Base-catalyzed reaction of 5-acylmethyl-2,5-di--butyl-4-oxa-2-cyclopentenones selectively derived from 4-alkyl-2,6-di--butylphenols three steps involving oxygenation, acetylation, and acid-treatment gave 3-alkyl-2,5-di--butyl-2,4-cyclopentadienones in excellent yield. 相似文献
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《Tetrahedron letters》1987,28(39):4529-4532
Cycloadditions of (E)-1-N-carbobenzoxyamino-1,3-butadiene to naphtoquinones followed by aromatization of the adducts and deprotection of the amino group afford regioselective syntheses of −5 and −8 substituted aminoanthraquinones. 相似文献
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A simple route to 1-R-3-(2-indolyl)-1-propanones has been elaborated based on recyclization of 2-(2-aminobenzyl)furan derivatives. Being a modification of the Reissert indole synthesis, our approach employs the furan ring as a source of carbonyl function. This approach is general and allows varying of substituents in aromatic ring as well as in 3-position of indole nucleus. 相似文献
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de Lucas A Fernández-Gadea J Martin N Martínez R Seoane C 《Rapid communications in mass spectrometry : RCM》2000,14(19):1783-1786
New substituted 2-amino-3-cyano-4H-pyrans have been studied by electron ionization (EI), chemical ionization (CI) and electrospray ionization (ESI) mass spectrometry. The retro-Diels-Alder reaction (RDA) is the main fragmentation pattern observed in the EI spectra forming an unsaturated ketone as the diene fragment. In contrast, a different RDA reaction takes place yielding an unsaturated amide as diene fragment together with the unsaturated ketone in the CI spectra. The MS/MS spectra obtained using an ESI source reveal that the favoured fragmentation by collision induced dissociation (CID) is the elimination of the substituent at the C4 position with formation of a stable pyrilium cation. 相似文献
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Butadiene cation radicals are produced symmetrically from the ring and side-chain of the vinylcyclohexene cation radical near the onset of the fragmentation. The appearance energies of C4H6+? and C4H2D4+? from (3,3,6,6-D4)vinylcyclohex ene were measured as 11.07 ± 0.05 and 11.06 ± 0.06 eV, respectively. This sets the barrier to retro-Diels-Alder decomposition at 1140 kJ mol?1 above the energy of 1 and 44 kJ mol?1 above the thermochemical threshold corresponding to C4H6+? + C4H6. Topological molecular orbital calculations indicate that this lowest-energy path involves a sequential rupture of the C3C4 and C5C6 bonds, with a calculated barrier of 211 kJ mol?1. The second, two-step reaction channel proceeds by subsequent fission of the C5C6 and C3C4 bonds with a barrier of 299 kJ mol?1. This channel is found experimentally as a break on the ionization efficiency curve at 12.1 eV. Both the supra-supra and the supra-antara pericyclic reactions go through energy maxima and are therefore forbidden. The supra-supra process is the most favorable route for decomposition from the first excited state, the activation energy being 333 kJ mol?1. The preference for the two-step mechanism is due to hyperconjugative stabilization of intermediate molecular configurations. 相似文献
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[reaction--see text] Dimerization of salicylaldehydes provided 6H,12H-6,12-epoxydibenzo[b, f][1,5]dioxocins in multigram quantities. Deprotonation-allylation of the benzylic acetals followed by further functionalization of the diallyl derivative and double Friedel-Crafts cyclization gave a novel preussomerin analogue which possessed the full carbon skeleton of the natural products. 相似文献
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A copper-catalyzed three-component reaction of 2-ethynylaniline, sulfonyl azide, and nitroolefin is reported. This reaction generates functionalized indoles in good yields and proceeds smoothly under mild conditions. Some hits as an HCT-116 inhibitor are found from the preliminary biological screening. 相似文献
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Maleimide-modified monolayer-protected gold nanoparticles (MPGN) are prepared from the protected furan-maleimide via the thermally reversible Diels-Adler reaction when required. These maleimide-MPGNs serve as a general platform allowing for a Diels-Alder reaction with furan-modified MPN to prepare larger 3D networks reversibly. [reaction: see text] 相似文献
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Tamiya M Ohmori K Kitamura M Kato H Arai T Oorui M Suzuki K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(35):9791-9823
A general approach to the regio- and stereoselective total synthesis of the benanomicin-pradimicin antibiotics (BpAs) is described. Construction of the aglycon has been achieved by 1) the diastereoselective ring-opening of a biaryl lactone by using (R)-valinol as a chiral nucleophile and 2) the stereocontrolled semi-pinacol cyclization of the aldehyde acetal by using SmI(2) in the presence of BF(3)OEt(2) and a proton source to afford the ABCD tetracyclic monoprotected diol. This strategy enabled us to control the two stereogenic sites in the B ring (C-5 and C-6) and the regioselective introduction of the carbohydrate moiety. The ABCD tetracycle could serve as an ideal platform for the divergent access to various BpAs. The amino acid (D-alanine) was introduced onto the ABCD tetracycle. Glycosylation was promoted by the combination of Cp(2)HfCl(2) and AgOTf (1:2 ratio). Construction of the E ring followed by deprotection completed the first total synthesis of benanomicin A (2 a), benanomicin B (2 b), and pradimicin A (1 a). The route is flexible enough to allow the synthesis of other congeners differing in their amino acid and carbohydrate moieties. 相似文献