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1.
A variety of 1-(-alkylphenyl)- and 1-(-'-dialkylphenyl)- pyrrolidines and -piperidines were prepared by the gas phase alumina mediated condensation of tetrahydrofuran (THF), tetrahydropyran (THP) or the corresponding diols with primary aromatic amines in fair to high yield. This methodology can also be used for the synthesis of 1-phenylhexahydroazepine from aniline. A mechanistic interpretation of the catalytic action of alumina is presented. 相似文献
2.
Epimestranol () is obtained in 80% yield from mestranol () by converting into its methanesulfonate and treating with silver(I) nitrate in a mixture of tetrahydrofuran and water. 相似文献
3.
Lithium N-butyl-4-pentenylamide () in tetrahydrofuran at 22 °C rearranged smoothly to give a mixture (after protonation) of 1-butyl-2-methylpyrrolidine, formed by an unusual cyclization process, and - and -N-butyl-3-pentenylamine; in the presence of 2.0 molar equiv of hexamethylphosphoramide, the total rate of isomerization was accelerated by a factor of 2.5. 相似文献
4.
Direct chlorination of 2-(2H-hexafluoropropyl)-tetra- hydrofuran gave high yield of 2-(2-chlorohexafluoropropyl)- pentachloro-2,5-dihydrofuran . Bromination of gave very complex mixture of products, from which three compounds, . 2-bromo-5-(2H-hexafluoropropyl)-furan , 3-bromo-5-(2H-hexafluoropropyl)-furan , and 2,4-dibromo-5-(2H-hexafluoropropyl)furan were isolated. Exchange fluorination of with dry KF at 240 – 300° led to a stepwise substitution of fluorines for chlorines to give mixtures of chloro-fluoro-2-(2-chlorohexafluoropropyl)-dihydrofurans ,, and , together with small amounts of 2-(2-chlorohexafluoropropyl)-3,4,5-trichlorofuran .Exchange fluorination of 3,4-dihalo-2,2,5,5-tetrafluoro- 2,5-dihydrofurans and led to a substitution of fluorine for one vinylic halogen to give 3-halo-2,2,4,5,5-pentafluoro-2,5-dihydrofurans and in good yields.Compounds – were characterised by n.m.r., m.s., and i.r. spectroscopy and elemental analysis. 相似文献
5.
Remarkable threo selectivity is observed in the reaction of aldehydes with - and -1-bromo-2-butene with the aid of chromium(II) salts. Solvent effect as well as the synthetic application is discussed. 相似文献
6.
On acetone-sensitization, 5-bromo-1,3-dimethyluracil ( reacts with Nb-methoxycarbonyltryptamine ( under the assistance of an electron carrier such as 2-methoxynaphthalene to give a coupling product . A mechanism involving a double electron transfer via the triplet state of is proposed. 相似文献
7.
When 3-bromo-5-phenyl-1,2,4-oxadiazole (1b) is heated with sodium azide in anhydrous dimethylformamide at 130°, 3-dimethylamino-() and 3-dimethylaminomethyleneamino-5-phenyl-1,2,4-oxadiazole () are formed, the latter by a new deoxygenative coupling of the azide (), or the nitrene derived from it, with the solvent. 相似文献
8.
Treatment of the di-lithium derivative of 1,2-diethynyl-benzene () with -xylene-α,α′-diol di--toluenesulphonate () in tetrahydrofuran led to 5,12-dihydronapthacene () as the only identifiable product. This reaction presumably involves 5,12-dihydro-6,11-didehydronaphthacene () as an intermediate, and this was confirmed by the formation of 5,12-dihydro-6,11-dideuterio-naphthacene when the reaction was carried out in tetrahydrofuran-8. 相似文献
9.
Two Novel long chain fatty acids, (5Z, 9Z)-6-bromo-25-methyl-5,9-hexacosadienoic and (5Z, 9Z)-6-bromo-24-methyl-5,9-hexacosadienoic acids were found in the phospholipids of and . Their structures were elucidated with the help of CI-EI7MS and a homogeneous hydrogenation catalyst. 相似文献
10.
Reaction of mucochloric and mucobromic acid with (ethoxycarbonylmethylene) triphenyl-phosphorane affords the ethyl ester of (2, 4 -4,5-dichloro- and (2, 4) -4, 5-dibromo-2,4-pentadienoic acid respectively; in the latter case ethyl (2 -5-bromo-2-penten-4-ynoate is formed concomittantly. 相似文献
11.
Claudio Fuganti Piero Grasselli Paolo Casati Massimo Carmeno 《Tetrahedron letters》1985,26(1):101-104
Baker's yeast reduction of ethyl 4-azido- and 4-bromo-3-oxobutyrate affords (3) (8) and (3) (2), respectively, in high optical purity. 相似文献
12.
Condensation of 3-fluoro-2-butanone () with alkyl diethylphosphonoacetates () gave alkyl 4-fluoro-3-methyl-2-pentenoates (). Addition of bromine yielded alkyl-2,3-dibromo-4-fluoro-3-methylpentanoates () which were dehydrobrominated to alkyl 2-bromo-4-fluoro-3-methyl-2- pentenoates (). Since these compounds could not be hydrogenated to the desired alkyl 2-bromo-4-fluoro-3-methylpentanoates (), another route was taken. The esters were hydrogenated to alkyl 4-fluoro-3- methylpentanoates () which were converted to their carbanions. Treatment with bromine gave esters , and iodine gave alkyl 4-fluoro-2-iodo- 3-methylpentanoates (). Esters and were converted to alkyl 2-azido-4-fluoro-3-methylpentanoates () whose hydrogenation gave alkyl 2-amino-4-fluoro-3-methylpentanoates (). Hydrolysis afforded γ-fluoroisoleucine (). 相似文献
13.
Heats of interaction of Lewis bases with hexameric and tetrameric alkyllithiums in hydrocarbon solution at 25° have been determined by high dilution solution calorimetry at low base to lithium atom ratios. The Lewis bases utilized include tetrahydrothiophene, tetrahydrofuran, triethylphosphine, triethylamine, and diethyl ether. The organolithiums investigated were -butyllithium, ethyllithium, isopropyllithium, trimethylsilylmethyllithium, and -butyllithium. The basicity order based on initial enthalpies of interaction is independent of the alkyllithium compound. Larger enthalpies of interaction were observed for the tetrameric hexameric alkyllithiums with the exception of tetrameric -butyllithium which does not interact significantly with these bases. The sensitivities of the enthalpies to the steric requirements of the base were probed by comparison of the enthalpies for tetrahydrofuran, 2-methyltetrahydrofuran, and 2,5-dimethyltetrahydrofuran. Base coordination to hexameric -butyllithium is more sensitive to the steric requirements of the tetrahydrofuran bases than is coordination to tetrameric trimethylsilylmethyllithium or isopropyllithium. These results are interpreted in terms of coordination of tetrahydrofuran bases to the intact hexameric aggregate for -butyllithium; however, it is concluded that the corresponding interaction with hexameric trimethylsilylmethyllithium leads directly to base-solvated tetramers. 相似文献
14.
The synthesis of five different 5,6-dideoxyhex-5-enofuranosides (, , and ) proceeds in 30–60% overall yield in two steps from commercially available 1--methyl pyranosides by reductive β-elimination of the intermediate 6-bromo-6-deoxypyranosides. 相似文献
15.
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
16.
Methyl 4-0-benzoyl-6-bromo-6-deoxy-α-D-glucopyranoside (, Figure 1) was converted, via the corresponding ditosylate , into methyl 2,3-di-0-p-toluenesulfonyl-4-0-benzoyl-6-S-acetyl-6-thio-α-D-glucopyranoside () by a selective nucleophilic displacement of 6-bromo-group with thioacetate. Unexpectedly, on treating the compound with an excess of sodium methoxide in benzene-methanol (1:1) at room temperature, methyl 2-0-p-toluenesulfonyl-4,6-thioanhydro-α-D-gulopyranoside () was obtained in a yield of 84%. In order to determine the structure of the relatively unstable oily product , some stable crystalline derivatives (, and ) were prepared. Detailed analysis of the 1H-NMR-spectra (200 MHz) of and gave the conclusive evidence for the structure of A self-imposing mechanism of the clean and smooth transformation of to is proposed, involving: a) formation of (Figure 2) as a crucial intermediate and b) a highly regioselective epoxide opening in (at C-4) by an intramolecular nucleophilic attack of the mercaptide anion from C-6. 相似文献
17.
3-bromo-2-(tert-butylsulfonyl)-1-propene 1 reacts in good yields with various electrophiles (aldehydes, ketones, nitriles and alkynes) in the presence of zinc metal to give unsaturated sulfones of type 4. These compounds can further react with soft or hard nucleophiles (alkyl-, vinyl-, aryllithium compounds, a nitroparaffin or dimethylmalonate) to yield highly functionnalized sulfones of type 5 which can be readily transformed into enones or into a dienone. Thus sulfone 1 is a versatile multi-coupling reagent which is synthetically equivalent to the synthon 8 and to the synthons 9 and 10. 相似文献
18.
Reaction of the amines (CF3)2NX (X=Cl,Br) with norbornadiene either in solvent (CH2Cl2) at ?78 °C in the dark or in the vapour phase at 20 °C in daylight gives a mixture of 3-halogeno-5-(-bistrifluoromethylamino)nortricyclene (, -and , -isomers) and -5-(-bistrifluoromethylamino)- -7-halogenonorbornene in quantitative yield formed halonium ion addition to the diene. The reaction of the amine (CF3)2NBr in solvent Me2O or Et2O at ?78 °C in the dark gives the same products in low yield, together with 3-bromo-5-alkoxynortricyclene (, - and , -isomers) and the amine (CF3)2NR (R=Me, Et) in high yield. 相似文献
19.
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
20.