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71.
Roman T. Gritsenko Pavel A. Belyakov Marina I. Struchkova Vladimir A. Tartakovsky 《Tetrahedron letters》2009,50(25):2994-2086
A method for the trifluoromethylation of enamines using Me3SiCF3 leading to α-CF3-substituted amines is described. The reaction is promoted by hydrofluoric acid generated from KHF2 and either trifluoroacetic or triflic acid, and involves protonation of the enamine followed by transfer of the CF3-carbanion from the silicon reagent to the cationic electrophile. 相似文献
72.
Randall N. Davis 《Tetrahedron》2009,65(48):9935-6573
Although carbaporphyrins and related systems have been widely studied, far less work has been carried out on the synthesis of porphyrin analogues with more than one carbocyclic subunit. Fulvene aldehydes are potentially valuable intermediates for studies of this type. A versatile methodology has been developed where benzaldehydes are reacted with an indene-derived enamine in the presence of dibutylboron triflate to give fulvene monoaldehydes. This chemistry allows halo, alkyl, methoxy or cyanovinyl units to be introduced and the resulting fulvenes are stable compounds that are easily purified by column chromatography. Isophthalaldehydes afford difulvene dialdehydes that are equally stable and these can be reduced with CeCl3-NaBH4 to give the related dicarbinols. The difulvene dialdehydes failed to give macrocyclic products when reacted with o-phenylenediamine in the presence of CeCl3 but instead gave unprecedented bis-indene-fused benzodiazepines. Fulvene monoaldehydes also reacted under these conditions to give benzodiazepine products in good yields. These results highlight the potential utility of fulvene aldehydes for synthetic applications both inside and outside of the area of porphyrin analogue chemistry. 相似文献
73.
Wieland Tyrra Dieter Naumann Sergej V. Pasenok Yurii L. Yagupolskii 《Journal of fluorine chemistry》1995,70(2):181-185
The reactions of ZnBr(CF3)·2CH3CN with 1-morpholinocyclo-pentene and -hexene have been investigated and found to yield mixtures of two isomers of 1-morpholino-1-cyanomethyl-2-difluoromethyl-cyclopentane and -hexane, respectively. The interaction with methylene bases of nitrogen heterocycles leads to the formation of trimethinecyanine dyes. This reaction sequence includes the formation of two carbon-carbon bonds in a one-pot operation. The mechanism of the reactions is discussed. 相似文献
74.
Henri Brunner Jörg Kraus Hans-Jürgen Lautenschlager 《Monatshefte für Chemie / Chemical Monthly》1988,119(10):1161-1167
Chiral enamines, obtained bySchiff base condensation from 1,3-dicarbonyl compounds and (R)-(+)-1-phenylethylamine, were found to undergo diastereoselectiveMichael reactions with ,-unsaturated carbonyl compounds. After removal of the chiral auxiliary (R)-(+)-1-phenylethylamine by hydrolysis, theMichael adducts were isolated in 59–95% optical yield.
Synthese von optisch aktiven Michaeladdukten via chirale Enamine
Zusammenfassung Chirale Enamine, durchSchiffbasenkondensation aus 1,3-Dicarbonylverbindungen und (R)-(+)-1-Phenylethylamin erhalten, gehen mit ,-ungesättigten Carbonylverbindungen diastereoselektiveMichaelreaktionen ein. Nach hydrolytischer Abspaltung des chiralen Hilfsstoffs (R)-(+)-1-Phenylethylamin werden dieMichaeladdukte in 59–95% optischer Ausbeute isoliert.相似文献
75.
Vadim A. Soloshonok Hironari Ohkura Manabu Yasumoto 《Journal of fluorine chemistry》2006,127(7):924-929
DBU-catalyzed asymmetric synthesis of (S)- and (R)-3-amino-4,4,4-trifluorobutanoic acid via enantioselective biomimetic transamination of isopropyl 4,4,4-trifluoro-3-oxobutanoate with (R)- and (S)-phenylethylamine has been developed. The effect of the base concentration of the reaction rate and stereochemical outcome has been systematically studied. The key reaction step, DBU-catalyzed 1,3-proton shift transfer was found to be highly enantioselective (>95% ee). However, due to some racemization of the intermediate Schiff base under the highly basic reaction conditions leads to the final product of lower enantiomeric purity. 相似文献
76.
We describe the preliminary results of one-pot syntheses of various N-substituted 2-methyl-4,5,6,7-tetrahydroindole derivatives from 2-(2-bromoallyl)cyclohexanone and the corresponding primary amines in good yields. Aliphatic amines were directly converted to tetrahydroindoles, whereas aromatic amines needed an extra base treatment step to complete the transformation. 相似文献
77.
Summary The reaction of cyclic enaminonitriles1 with diethyl acetonedicarboxylate (2) affords fused 4-amino-3-ethoxycarbonyl-2-ethoxycarbonylmethyl-pyridines4. The course of the reaction and the yield of cyclic products were promoted by tin(IV)chloride. N-substituted diethyl 3-aminoglutaconates3 seem to be intermediates of the cyclization reaction.Dedicated to Prof.Milan Kratochvil on the occasion of his 70th birthday 相似文献
78.
《Tetrahedron》2019,75(46):130661
This paper reports progress in the development of a furan oxidative N-spirocyclisation approach to the fawcettimine alkaloids huperzine Q and lycopladine D. A short synthesis is described of a key intermediate cyclopentaindolizidine that subsequently fragments by N-acylation and β-elimination. The stereochemistry of 1,4-addition of cyanide to the resulting enone is discussed with supporting molecular modelling calculations. N-Deprotection is shown to be accompanied by cyclisation onto the nitrile group, resulting in a tricyclic lactam with a twisted amide functionality. Elaboration of this lactam afforded four of the five rings present in lycopladine D with just the C(8) carbon lacking. 相似文献
79.
Koichiro Kase Tsutomu Konno Hiroki Yamanaka John T Gupton 《Journal of fluorine chemistry》2003,120(1):33-39
β-Trifluoroethoxy vinamidinium salts 1 reacted smoothly with various types of the carbanions, generated by treatment of ketones, esters, amide and nitriles with LDA, to give the corresponding trifluoroethoxylated multifunctional dienamine derivatives 3 in moderate to good yields. On the other hand, the reaction of 1 with lithium acetylide and other carbanions derived from methyl compounds bearing sulfonyl, sulfinyl, and phosphonyl groups produced the corresponding α,β-unsaturated aldehydes 5 in good yields. 相似文献
80.
Condensation of alkyl -haloacetoacetates (or -chloroacetoacetanilide) with triethoxymethane and primary (hetero)aromatic amines gives in a one step synthesis under mild conditions new ,-diacyl-enamines (2 a-m, 3 a-d). In contrast, the N-alkylsubstituted derivatives could be synthesized only in a two step procedurevia the enolethers6 a, b. According to their ir-specra, most of the aminomethylene--haloacetoacetic acid derivatives are stereochemically fixed either in theE- orZ-form. The pmr-spectra, however, show that they exist as mixtures of at least two isomers in solution.With KOH or sodium acetate, a ring closure to 3-hydroxy-pyrroles (8, 9) could be achieved whereas with pyridine only quarternary pyridinium salts (11) are formed. Acidic (orLewis acidic) condensing agents leave the chloroacetyl group unaffected and give either free carboxylic acids (2 p-r) pyrido-[1,2-a]pyrimidones (12) or 4-quinolones (13), depending on the type of the molecule and the reaction temperatures employed.
Synthesen von Aminomethylen--halogenacetessigsäurederivaten und deren Ringschlußreaktionen zu 3-Hydroxypyrrolen, Pyrido[1,2-a]pyrimidonen bzw. 4-Chinolonen ,-Diacyl-enamine und-enole, 5. Mitt.相似文献