共查询到20条相似文献,搜索用时 134 毫秒
1.
Tetraphenylporphyrin-sensitized photooxygenation of cycloheptatriene afforded the 1,2-dioxetane () in 9% yield, thus completing the set of possible cycloaddition products; the 1,2-dioxetane () is the precursor to the benzaldehyde product, but not the (2+6)-cycloadduct (). 相似文献
2.
Jack E. Baldwin Robert M. Adlington Bernard J. Rawlings Richard H. Jones 《Tetrahedron letters》1985,26(4):485-488
Practical procedures for the resolution of racemic modification of (1, 2)-and (1, 2)-1-amino-2-ethylcyclopropane-1-carboxylic acid ,,(1, 2)- and (1, 2)-1-amino-2-methylcyclopropane-1-carboxylic acid ,, and (1, 2)- and (1, 2)-1-amino-2-methylcyclopropane-1-carboxylic acid , are described; the structures as ,, and were confirmed by X-ray-crystallographic methods. 相似文献
3.
Reaction of () and () with the acetal () in presence of trimethylsilyl trifluoromethanesulfonate at ?70° C gives the α-glucosides () and (), whereas () and () lead to the β-glucosides () and (). At 0° C reaction of () with the acetals () gives exclusively the α-glucosides (). 相似文献
4.
Takashi Toda Norihiko Shimazaki Toshio Mukai Chizuko Kabuto 《Tetrahedron letters》1980,21(41):4001-4004
The structure of a minor dimer () of 1-arylcycloheptatrienylidenethylene was determined by X-ray crystallography. Dehydration of and gave novel non-benzenoid aromatics---6,12-diarylazuleno[1,2-b]azulenes ( and ), whose electronic and NMR spectral properties were reported. 相似文献
5.
Ernst-Ulrich Würthwein Jayaraman Chandrasekhar Eluvathingal D Jenmis Paul von Ragué Schleyer 《Tetrahedron letters》1981,22(9):843-846
Semi-empirical (MINDO/3 and UNDO) MO calculations on highly strained planar tetracoordinate carbon candidates indicate the central carbons in - [4.4.4.4] fenestrane () to have pyramidal () and in trans-[4.4.4.]fenestrane () to have distorted tetrahedral () geometries. In [2.2.2.2]paddlane (), the two central carbons are pentacoordinate. Each is nearly coplanar with four carbon neighbours; additionally, the two bridgehead carbons are connected by a single bond (). 相似文献
6.
Yasuo Sakai Shingo Toyotani Yoshito Tobe Yoshinobu Odaira 《Tetrahedron letters》1979,20(40):3855-3856
Oxidative decarboxylation of [n.2.2]propellane carboxylic acids (-) with lead tetraacetate gave the bicyclic acetates (, ) having a bridgehead double bond and/or the tricyclic acetates (, ) in good yields. Vapor phase thermolysis of or afforded the bridgehead olefin or quantatively. 相似文献
7.
The coupling between the 5-chloro-3-en-1-ynes - and trimetylchlorosilane gives rise to the vinylallenes - substituted by a trimethylsilyl group on the allenic moiety. 相似文献
8.
Methods of substituting pyridine by perhalogenomethylmercapto groups are discussed. The side chain chlorination of 2-(methylmercapto)pyridine leads gradually to 2-(trichloromethylmercapto)pyridine hydrochloride () and 2-(trichloromethylmercapto)pyridine (). Neither a direct reaction of pyridine with CF3SCl nor the way over a Grignard reaction or a sulfenylcarboxylate lead to CF3S-substituted products. Reactions of pyridine and bromopyridines with Hg(SCF3)2 yield 1:1-adducts () only. Lithium tetrakis(1,2-dihydro-1-pyridyl)aluminate (LDPA) reacts with CF3SCl to give 3-(trifluoromethylmercapto)pyridine (); in addition a disubstituted product can be identified massspectroscopically. 1H- and 19F-NMR-spectra are reported. 相似文献
9.
In a synthetic approach to macrostomine , both side chains of the isoquinoline nucleus are attached by high yield carbon carbon bond formation with lithiated nitrosamines ( → , → ). 相似文献
10.
Reaction of the hydroaromatic compounds () and () with lithium-diisopropylamide followed by phenylselenenyl chloride gives the selenides () and () resp. (), which form exclusively the phenols () resp. () after oxidation with 3-chloroperbenzoic acid in the presence of 3,5-dimethoxyaniline (). 相似文献
11.
Reaction of the tricyclic epoxides () and () with boron trifluoride etherate leads to fluorohydrins () and () derived in the novel fluoride transfer, whereas () undergoes isomerization to spiro ketone (). 相似文献
12.
A facile synthesis of the title compounds ( and ) is described; key steps include the mono-C-alkylation of the glycine Schiff base benzyl ester with α-bromo-α-fluorotoluene, which provides the readily separable fluorinated diastereomers and , and the dealkylative hydrolysis of the benzyl esters - without concomitant loss of the benzylic fluorine. 相似文献
13.
The title intermediate () is produced on photolysis of hexakis(2,6-diethyl-phenyl)cyclotrigermane () or bis(2,6-diethylphenyl)bis(trimethylsilyl)germane () as evidenced by trapping experiments, and thermally dimerizes to tetrakis(2,6-diethyl-phenyl)digermene (). Diarylgermylenes such as do not form stable triethylamine adducts (e.g. ) as has been previously reported. 相似文献
14.
The synthesis of the 2,4,6-cycloheptatrienyl ketones – by two alternative routes is reported: Route 1): The adducts from the phenyl(trimethylsiloxy)-acetonitriles , known as “umpolung” reagents, and tropylium tetrafluoroborate are cleaved by triethylammonium fluoride to form the aromatic cycloheptatrienyl ketones –. Route 2): the phenyl, methyl, and cyclopropyl ketone (, , ) are prepared by treatment of the acid chloride with the corresponding organomanganese iodides RMnI (, , ). The Fe-catalyzed coupling reaction of the acid chloride with a Grignard reagent was also used for the preparation of ketone . 相似文献
15.
The diene reacted with CHCl3/aq. NaOH/PTC in CH2 Cl2 unexpectedly to give a mixture of the chlorination products and . Usual chlorination with Cl2 yielded similarly , , and dependent on the amount of Cl2. The formation of as well as the reaction of to give (besides ) shows an unusual Cl-Cl-interaction. 相似文献
16.
Takehiko Nishio Katsuhiro Katahira Akira Kato Choji Kashima Yoshimori Omote 《Tetrahedron letters》1979,20(43):4211-4212
Irradiation of N-aryl-2(1H)-pyrimidin-2-ones (-) in a mixed benzene-alcohol solution afforded the products initiated by Type I cleavage, 1-(3-alkoxycarbonylamino-2-propene)-N-arylimines (-, , and ) in 45–51% yields. 相似文献
17.
The model tripeptide Boc-Gly-S-Ala-Aib-OMe () and the two monothiated analogues Boc-Gly(1ψ2CSNH)-S-Ala-Aib-OMe () and Boc-Gly-S-Ala(2ψ3 CSNH)-Aib-OMe () were synthesized. Peptide was obtained by thiation of using 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide, Lawesson's Reagent (LR), followed by deprotection of the Boc group and coupling with Boc-Gly-OH. Thiation of with LR regiospecifically transformed the protected tripeptide to the monothiated analogue . X-Ray diffraction analysis showed that the type-III β-turn formed by the reference peptide is preserved in the monothiated analogue ; conversely,the structure of the isomeric tripeptide is partially extended. 相似文献
18.
Isomerization of -bicyclo[10.8.0]eicos-1(12)-ene () and -bicyclo[10.10.0]docos-1(12)-ene () to [10.8]- and [10.10]betweenanene ( and ) has been effected by sulfuric acid. In both cases, the betweenanene isomers were found to predominate at equilibrium (70/30 / and 95/5> /). 相似文献
19.
N,N-Dimethylformamide () and N,N-dimethylpivalamide () react with carbonyl chloride isocyanate () in the presence of antimony pentachloride to afford the amino substituted 1-oxa-3-azabutatrienium hexachloroantimonates ,. An X-ray diffraction analysis of confirms the proposed structure. The heterocumulenes , react with aldehydes, ketones and tertiary carboxamides to give the amino substituted 2-azaallenium salts - in high yields. 相似文献
20.
The N-hydroxyazetidines and are prepared startinfrom 2,3-dihydroazete 1-oxides ( and 0 by reduction with sodium borohydride and by reaction with a nucleophile, respectively. The N-thydroxyazetidines and can be oxidized with mercury (II) oxide to the corresponding nitrones ; oxidation of the N-hydroxyazetidine (unsubstituted at C-4) with equivalent of lead tetraacetate tyields the N-tacetoxy β-lactam . 相似文献