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1.
A total synthesis of bistratamide H has been achieved using a new ‘highly’ fluorous amino protecting group, tris(perfluorodecyl)silylethoxylcarbonyl (FTeoc) group. The synthetic intermediates were easily isolated by liquid-liquid extraction with fluorous solvent. The fluorous protecting group was demonstrated to be recycled.  相似文献   

2.
Fluorous-tagged protecting groups are attractive tools for elongating carbohydrate chains in oligosaccharide synthesis. To eliminate the accumulation of failed sequences during automated oligosaccharide synthesis conditions, an additional C8F17 ester derived protecting group was attached to the glycosyl donor to better retain the desired doubly tagged glycosylation product on fluorous solid-phase extraction (FSPE) cartridges. Initial studies show that the double-fluorous-tagging strategy offers a robust enough separation using a commercial FSPE cartridge using simple gravity filtration to separate the desired product from the singly fluorous-tagged starting materials and their decomposition products. In addition, removal of the fluorous acetate and its by-products after sodium methoxide treatment and neutralization required only dissolution of the desired sugar in toluene and subsequent removal of the toluene layer from the denser fluorous by-products.  相似文献   

3.
N,N-Bis(perfluoroalkyl)thiocarbamoyl chlorides (FDMTC-Cls) were synthesized as reagent for the protection of alcohols. Using the crystalline FDMTC-Cls, the FDMTC groups were introduced into the alcohol molecules in excellent yields in the presence of sodium hydride in THF at room temperature. The products were separated from the excess alcohols by solid-phase extraction with a fluorous reverse-phase silica gel column (Fluorous Solid Phase Extraction; FSPE). The FDMTC groups were readily removed by oxidation with m-chloroperbenzoic acid (m-CPBA) and subsequent hydrolysis with KHCO3.  相似文献   

4.
Yangen Huang 《Tetrahedron》2004,60(38):8341-8346
Fluorous glycol derivatives 5 were prepared and evaluated as reagents for the protection of carbonyl groups for use in fluorous synthesis. The acetals formed from fluorous diol 5b (Rf=n-C8F17) with carbonyl compounds can be separated and purified by simple fluorous-organic extraction.  相似文献   

5.
The catalyst of rare earth(III) perfluorooctanesulfonates (RE(OSO2C8F17)3, RE = Sc, Y, La-Lu) were prepared from either rare earth chlorides(III) or oxides and perfluorooctanesulfonic acid. The perflates thus obtained act as novel catalysts for Friedel-Crafts alkylation in fluorous biphasic system. Perfluorohexane (C6F14), perfluoromethylcyclohexane (C7F14), perfluorotoluene (C7F8), perfluorooctane (C8F18), perfluorooctyl bromide (C8F17Br) and perfluorodecalin (C10F18, cis- and trans-mixture) can be used as fluorous solvents for this reaction. By simple separation of the fluorous phase containing only catalyst, alkylation can be repeated many times.  相似文献   

6.
A practical, efficient, and environmentally benign intramolecular hydroamination of olefinic sulfonamides was carried out in fluorous biphase system (FBS) using commercially available heptadecafluorooctanesulfonic acid (C8F17SO3H) as a catalyst and perfluorodecaline (C10F18, cis- and trans- mixture) as a fluorous solvent to produce the corresponding cyclic products in good yields. The Brønsted acid of C8F17SO3H is easily recovered and recycled at least five times.  相似文献   

7.
Min Shi  Shi-Cong Cui  Ying-Hao Liu 《Tetrahedron》2005,61(21):4965-4970
In this paper, we describe a useful Mannich-type reaction in fluorous phase. By use of perfluorodecalin (C10F18, cis- and trans-mixture) as a fluorous solvent and perfluorinated rare earth metal salts such as Sc(OSO2C8F17)3 or Yb(OSO2C8F17)3 (2.0 mol%) as a catalyst, the Mannich-type reaction of arylaldehydes with aromatic amines and (1-methoxy-2-methylpropenyloxy)trimethylsilane can be performed for many times without reloading the catalyst and the fluorous solvent.  相似文献   

8.
2,2,2-Trifluoroethanol, 1,1,1,3,3,3-hexafluoro-2-propanol, and nonafluoro-tert-butyl alcohol were used as precursors for the preparation of the appropriate bis(polyfluoroalkoxymethyl)carbinols [(RFHOCH2)2CHOH, 1a-c, RFH = (a) CF3CH2, (b) (CF3)2CH, and (c) (CF3)3C] and the corresponding mesylates [(RFHOCH2)2CHOSO2CH3, 2a-c]. This novel design paradigm is introduced to eliminate the persistence and bioaccumulation problems of fluorous chemistry, which are associated with the use of longer linear perfluoroalkyl groups (e.g. Rfn ≥ n-C8F17, n-C7F15). Secondary mesylates 2a,b and the primary tosylate [(CF3)3COCH2CH2OTs, 2d] displayed acceptable reactivity towards azide and imidazole nucleophiles to allow the syntheses of novel fluorous azides, which on hydrogenolysis with H2/Pd-C offered fluorous amines [(RFHOCH2)2CHNH2, 8a,b], and 1-(polyfluoroalkyl)imidazoles (5a,b,d), respectively, while 2c showed no reactivity due to steric hindrance. The reaction of 8a,b with formaline, glyoxal and hydrochloric acid gave symmetrical 1,3-dialkylated imidazolium chlorides (9a,b), while 5a,b,d were effectively alkylated using n-C8F17(CH2)3I, methyl iodide, 2-bromoethanol, and 2d to yield the corresponding 1,3-dialkylimidazolium iodides, bromides, and tosylates (7aa-ec). Some physical properties of new compounds including mp, bp and solubility patterns were also analyzed; and the fluorophilicity values of 1a-c, and 2a-c were experimentally determined by GC and/or 19F NMR spectroscopy.  相似文献   

9.
A recyclable and reusable (S) diphenylpyrrolinol silyl ether I organocatalyst bearing a n-C8F17 fluorous tag has been demonstrated for promoting the asymmetric Michael addition reactions of a wide range of aldehydes with both aryl and alkyl-substituted nitroolefins and excellent levels of enantio- and diastereoselectivities are achieved. The catalyst I can be conveniently recovered by fluorous solid-phase extraction and subsequently reused (up to eight cycles) without significant loss of its catalytic activity and stereoselectivity for the process.  相似文献   

10.
(Nonafluoro-tert-butyloxy)ethyl tosylate 4 was prepared in 65% yield from nonafluoro-tert-butanol 1 using commercially available reagents. Further reaction of 4 with HNR1R2 (R1 = R2 = H, CH3; R1 = H, R2 = CH3, (CH2)3C8F17, CH2CH2OC(CF3)3) affords the appropriate (CF3)3COCH2CH2NR1R2 amines in 20-69% yields. Improved overall yields of [(CF3)3COCH2CH2]3−nNRn to 1 were obtained by the reaction of (CF3)3CONa 2 and (XCH2CH2)3−nNRn (X = Cl, n = 0, 1, 2, R = CH3; X = CH3SO2O, n = 1, R = CH3SO2) nitrogen mustards and a similar reactive β-substituted ethyl amine. The title amines are mobile colorless liquids and volatile with steam. The bulky fluorous ponytail (CF3)3CO(CH2)2 displays high acidic stability and increases fluorous character almost as much as the classical straight-chain C8F17(CH2)3 ponytail.  相似文献   

11.
Catalytic Friedel-Crafts acylation of benzene and unactivated benzenes, such as chlorobenzene and fluorobenzene, was successfully accomplished using rare earth(III) perfluorooctane sulfonates (RE(OPf)3), RE = Sc, Y, La ∼ Lu) and perfluorooctanesulfonic acid (PfOH) as catalysts in fluorous solvents. Solutions of Yb(OPf)3 and PfOH in perfluorodecalin (C10F18, cis and trans-mixture) are the most suitable catalytic system, with catalyst loading as low as 0.4%mol leading to clean, high-yielding benzoylation of a variety of unactivated benzenes. By simple separation of the fluorous phase containing only catalyst, acylation can be repeated several times.  相似文献   

12.
A series of fluorinated bipyridine derivatives, (4,4′-bis(RfCH2OCH2)-2,2′-bpy) {Rf = n-C8F17 (1a), n-C9F19 (1b), n-C10F21 (1c), n-C11F23 (1d)} have been successfully synthesized using 4,4′-bis(bromomethylene)-2,2′-bpy and fluorinated alkoxides. Bpy 1a-d have been characterized by multi-nuclei (1H, 19F, and 13C) NMR, GC/MS and FTIR. The Cu complexes 2a-d could be generated in situ by stirring ligands 1a-d with CuBr·Me2S at room temperature, respectively. The 3-component systems 3c-d, CuBr·Me2S/Bpy (1c-d)/2,2,6,6-Tetramethylpiperidine 1-oxyl (TEMPO), were successfully used to the aerobic oxidation of alcohols under the fluorous biphasic system (FBS). The resulting products from FBS could be easily recovered by two phase separation with high yields up to 8 runs (>90%). In order to avoid using the expensive fluorous solvents, systems 3a-d, CuBr·Me2S/Bpy (1a-d)/TEMPO, were also successfully shown to catalyze the aerobic alcohol oxidation under the thermomorphic condition (in C6H5Cl), and the yields of oxidation of 4-nitrobenzyl alcohol were close to 100% even after 8 runs. In particular, 3a was most effective under the thermomorphic mode in the chemoselectivity of aerobic oxidation of aliphatic primary alcohols to aldehydes without any overoxidized acids.  相似文献   

13.
Dithiophosphoric acids [HS2P(OC2H4CnF2n+1)2] (n = 4, 6) have been prepared in high yields. Deprotonation and reaction with transition metal substrates affords fluorous metal complexes which have been characterised by elemental analysis, mass spectrometry, IR and NMR spectroscopies. The structures of [Cu{S2P(OC2H4CnF2n+1)2}(PPh3)2] (n = 4, 6) and [Cu{-S2P(OC2H4C4F9)2}(PPh3)]2 have been determined by single crystal X-ray diffraction.  相似文献   

14.
The paper describes the polarities of three fluorous (F) aliphatic alcohols: perfluorinated tert-butanol (F-t-BuOH), n-butanol (F-n-BuOH), and n-heptanol (F-n-HepOH). For the purpose, we conducted absorption and fluorescence spectroscopies of coumarin 153 (C153) and 102 (C102) in three F and 13 non-fluorous (non-F) alcohols and determined their maximum energies: νa (absorption) and νf (fluorescence). We obtained linear relationships between the Stokes shifts of the dyes (i.e., (νa − νf)) and a medium polarity parameter for 13 non-F alcohols, f(x): f(x) = [(Ds − 1)/(2Ds + 1) − (n2 − 1)/(2n2 + 1)], where Ds and n were the dielectric constant and refractive index of a solvent, respectively. By comparing the Stokes shifts of the dyes in three F alcohols with those in 13 non-F alcohols (i.e., (νa − νf) vs. f(x) plot), the Ds values in F-t-BuOH, F-n-BuOH, and F-n-HepOH were evaluated to be 2.7-3.9, 4.3-5.1, and 4.0-5.2, respectively, while those in the relevant non-F alcohols were 12.5, 17.5, and 12.9, respectively. Thus, the present experiments demonstrated that the polarities of these F alcohols were much lower than those of the relevant non-F alcohols.  相似文献   

15.
In fluorous biphase system, hafnium(IV) bis(perfluorooctanesulfonyl)amide complex (Hf[N(SO2C8F17)2]4) was found to be a highly reactive and recyclable Lewis acid catalyst for Friedel-Crafts acylation and Prins reaction at significantly low catalyst loadings (≤1 mol%). In these reactions, Hf[N(SO2C8F17)2]4 is selectively soluble in the lower fluorous phase and can be recovered simply by phase separation. Furthermore, the catalyst can be reused without decrease of activity.  相似文献   

16.
Debaprasad Mandal 《Tetrahedron》2010,66(5):1070-1077
Perfluoromethyldecalin solutions of the fluorous alkyl halides Rf8(CH2)mX (m=2, 3; X=Cl, I) are inert toward aqueous NaCl, KI, KCN, and NaOAc. However, substitution occurs at 100 °C in the presence of 10 mol % of the fluorous ammonium salts (Rf8(CH2)2)(Rf8(CH2)5)3N+ I (1) or (Rf8(CH2)3)4N+ Br (2) (10 mol %), which are fully or partially soluble in perfluoromethyldecalin under these conditions. Stoichiometric reactions of (a) 1 and Rf8(CH2)3Br, and (b) 2 and Rf8(CH2)2I are conducted in perfluoromethyldecalin at 100 °C, and yield the same Rf8(CH2)mI/Rf8(CH2)mBr equilibrium ratio (60-65:40-35). This shows that ionic displacements can take place in extremely nonpolar fluorous phases, and suggests a classical phase transfer mechanism for the catalyzed reactions. Interestingly, the non-fluorous ammonium salt mixture CH3(CH3(CH2)m)3N+ Cl (3, Aliquat® 336; m=2:1 7/9) also catalyzes halide substitutions, but under triphasic conditions with 3 suspended between the lower fluorous and upper aqueous layers. NMR experiments establish very low solubilities in both phases, suggesting interfacial catalysis.  相似文献   

17.
A series of fluorinated β-diketones, RfC(O)CH2C(O)Rf (Rf=C6F13, Rf′=CF3; Rf=Rf′=C6F13, C7F15), have been prepared in reasonable yields by a two-step synthesis. On reaction with appropriate metal substrates, deprotonation and concurrent coordination of the perfluoroalkyl-derivatised β-diketonate ligands affords a range of fluorous metal complexes which have been characterised by elemental analysis, mass spectrometry, IR and NMR spectroscopies. The structures of [Cu(L-L)2(H2O)2] {L-L=CF3C(O)CHC(O)C6F13, C6F13C(O)CHC(O)C6F13} and [Cu(PPh3)2{C7F15C(O)CHC(O)C7F15}] have been determined by single-crystal X-ray diffraction.  相似文献   

18.
Carbohydrate glycosyl acceptor and donor moieties were synthesized efficiently by using the fluorous tag method. The p-alkoxyphenyl-type heavy fluorous tag was stable under all the reaction conditions used in the preparation of the various carbohydrate units. Each synthetic intermediate carrying the fluorous tag could be obtained in a simple straightforward manner by partition between fluorous and organic solvents.  相似文献   

19.
20.
Xiuhua Hao 《Tetrahedron letters》2005,46(15):2697-2700
In a fluorous biphase system, Hf[N(SO2C8F17)2]4 complex (1 mol %) catalyzes Friedel-Crafts acylation of aromatic compounds such as anisole, toluene and chlorobenzene, and the corresponding aromatic ketones are obtained in satisfactory to high yields. The catalyst is selectively soluble in lower fluorous phase and can be easily recovered by simple phase separation. Furthermore, the catalyst can be reused without decrease of activity in most cases.  相似文献   

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