Yb[N(SO2C8F17)2]3-catalyzed allylation of 1,3-dicarbonyl compounds with allylic alcohols in a fluorous biphase system

Allylation of 1,3-dicarbonyl compounds with allylic alcohols was successfully accomplished using rare earth metal (III) bis(perfluorooctanesulfonyl)imide [RE(NPf₂)₃, RE = La∼Lu] as catalysts in fluorous solvents. Ytterbium bis(perfluorooctanesulfonyl)imide [Yb(NPf₂)₃] catalyzes the high efficient reaction of allylation in fluorous solvents. By simple separation, fluorous phase containing only catalyst can be reused several times.     

A new application of cerium(IV) ammonium nitrate [(NH4)2Ce(NO3)3] in fullerene chemistry—free-radical alkoxylation of C60 fullerene on reaction with primary alcohols

The reaction of [60]fullerene with primary aliphatic alcohols (ROH, R = Et, Me, Pr) mediated by cerium(IV) ammonium nitrate [(NH₄)₂Ce(NO₃)₃] affords the corresponding alkoxy-derivatives with a hydroxy group, C₆₀(OR)_x(OH) (x = 3, 4) in high yield. The reaction is characterized by a free radical mechanism confirmed by an EPR study of the alkoxy fullerenyl radical (g = 2.0023).     

Reduction of ketones to corresponding alcohols with magnesium metal in absolute alcohols

Various aliphatic and aromatic ketones are treated with 10 equiv of magnesium metal in absolute methanol or ethanol to afford corresponding alcohols in very high yields at room temperature within 12 h.     

A spectroscopic study on medium polarity in fluorous alcohol

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: ν^a (absorption) and ν^f (fluorescence). We obtained linear relationships between the Stokes shifts of the dyes (i.e., (ν^a − ν^f)) and a medium polarity parameter for 13 non-F alcohols, f(x): f(x) = [(D_s − 1)/(2D_s + 1) − (n² − 1)/(2n² + 1)], where D_s 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., (ν^a − ν^f) vs. f(x) plot), the D_s 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.     

Efficient, recoverable, copper-free Sonogashira reaction under FBS and thermomorphic mode

The solubility property of high fluorine content ligands allows us to report in this article the accomplishment under the fluorous biphasic system (FBS) the Pd-catalyzed Sonogashira reactions using novel recyclable Pd catalysts with fluorous-ponytails in the structure of 2,2′-bpy ligands that are only soluble in perfluorinated solvents at room temperature. Alternatively, without using any fluorous solvent but under the thermomorphic mode, the same Pd catalysts proceed with the Cu-free Sonogashira reactions homogeneously in DMF at 135 ± 5 °C, whereas the product mixtures after reaction remain in solution and the Pd catalysts precipitate from DMF at low temperature.     

A highly efficient and recyclable silica-supported palladium catalyst for alcohol oxidation reaction

A silica supported palladium catalyst (SiO₂@APTES-Pd) showed excellent activity and reusability for selective oxidation of alcohols to corresponding carbonyl compounds with H₂O₂ as oxidant under base free environment. A wide range of alcohols including aliphatic alcohols are tolerated as substrates with a low loading of palladium (0.1 mol %).     

Combining lipase-catalyzed enantiomer-selective acylation with fluorous phase labeling: a new method for the resolution of racemic alcohols

Lipase-catalyzed acylation of racemic alcohols with a highly fluorinated acyl donor allows their kinetic resolution accompanied by the simultaneous enantiomer-selective fluorous phase labeling. Both the tagged and the untagged enantiomer can be separated without chromatography by a very efficient partition between a fluorous and an organic phase. The method has been successfully applied to the resolution of typically racemic secondary alcohols of low molecular weight. The fluorous label can be recovered quantitatively.     

Cobalt(II) catalyzed tosylation of alcohols with p-toluenesulfonic acid

Cobalt(II) chloride hexahydrate (CoCl₂·6H₂O) has been found to catalyze the tosylation of both aliphatic and aromatic alcohols with p-toluenesulfonic acid (p-TsOH) in high yields in 1,2-dichloroethane under reflux (ca. 80 °C). In the case of aliphatic alcohols, secondary alcohols undergo tosylation chemoselectively in the presence of primary hydroxy groups.     

Ytterbium perfluorooctanesulfonates catalyzed synthesis of benzimidazole derivatives in fluorous solvents

Catalytic condensation of o-phenylenediamine and aldehydes was accomplished using rare earth(III)perfluorooctane sulfonates (RE(OPf)₃), RE = Sc, Y, La ∼ Lu) as catalysts in fluorous solvents. Ytterbium perfluorooctanesulfonates (Yb(OPf)₃) catalyzes the high-efficient synthesis of benzimidazole derivatives in fluorous solvents. By simple separation, fluorous phase containing only catalyst can be reused several times.     

Microwave-assisted nickel(II) acetylacetonate-catalyzed arylation of aldehydes with arylboronic acids

Applying sealed vessel microwave heating at 180 °C in toluene the arylation of aromatic and aliphatic aldehydes with arylboronic acids using 1-2 mol % of Ni(acac)₂ as a catalyst can be performed efficiently within 10-30 min providing the desired diarylmethanols or benzyl alcohols in good yields.     

Iridium-catalyzed oxidative esterification reaction of aliphatic aldehydes and olefinic alcohols with precoordination of the double bond of alcohols to iridium

A novel iridium-catalyzed oxidative esterification reaction of aliphatic aldehydes and olefinic alcohols in toluene was found under mild conditions of [IrCl(cod)]₂ (5 mol %) in combination with K₂CO₃ (10 mol %) at rt.     

Hf[N(SO2C8F17)2]4-catalyzed Friedel-Crafts acylation in a fluorous biphase system

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.     

An effective and catalytic oxidation using recyclable fluorous IBX

Oxidation of alcohols in the presence of a catalytic amount of fluorous IBX and Oxone as a co-oxidant resulted in the corresponding carbonyl compounds in good to high yields. The fluorous IBX is readily recovered as insoluble fluorous IBA from the reaction mixture by simple filtration, and can be reused without significant loss of the catalytic activity.     

A convenient and highly efficient method for the protection of aldehydes using very low loading hydrous ruthenium(III) trichloride as catalyst

A convenient method for the chemoselective protections of both aliphatic and aromatic aldehydes has been developed. Ruthenium(III) trichloride (0.1 mol %) has found to be an highly efficient catalyst in the acetalizations of aldehydes with various simple alcohols such as methanol, ethanol, or diols such as 1,2-ethylanediol and 1,3-propanediol under mild reaction conditions.     

Novel fluorous prolinol as a pre-catalyst for catalytic asymmetric borane reduction of various ketones

Novel prolinol carrying two perfluorohexylethyl groups at the α-position was prepared from l-proline as a starting chiral substrate. Catalytic asymmetric reduction of various ketones, including mono-, di-, and trifluoromethylated acetophenones, using fluorous oxazaborolidines derived from fluorous prolinol afforded the corresponding alcohols in good to excellent yields and with high enantioselectivities (up to 93.2% ee). The fluorous prolinol was recovered without any fluorous solvents or silica gel by simply cooling the organic phase and filtration.     

Ytterbium perfluorooctanesulfonate as an efficient and recoverable catalyst for the synthesis of trisubstituted imidazoles

Synthesis of trisubstituted imidazoles was successfully accomplished using rare earth(III) perfluorooctanesulfonates (RE(OPf)₃), RE = Sc, Y, La-Lu as catalysts in fluorous solvents. Ytterbium perfluorooctanesulfonates (Yb(OPf)₃) catalyze the high efficient synthesis of trisubstituted imidazoles in fluorous solvents. By simple separation, fluorous phase containing only catalyst can be reused several times.     

An expeditious synthesis of hexahydrobenzo[f]isochromenes and of hexahydrobenzo[f]isoquinoline via iodine-catalyzed Prins and aza-Prins cyclization

Homoallylic alcohols (primary, secondary, or tertiary containing an endocyclic or an exocyclic double bond) react with equimolar amounts of aldehydes (aliphatic or aromatic) and ketones (aliphatic) in the presence of 5 mol % of iodine. This Prins cyclization was used in the preparation of hexahydrobenzo[f]isochromenes and of a 4-hydroxy-tetrahydropyran, in 54-81% yield. The procedure is also efficient for an aza-Prins cyclization of a homoallylic sulfonamide and benzaldehyde, producing a hexahydrobenzo[f]isoquinoline.     

Ammonium salt catalyzed oxidation of organosulfides to organosulfoxydes

The selective oxidation of aromatic and aliphatic organosulfides with H₂O₂/H₂O catalyzed by metal free ammonium salts has been explored. Reactions were performed using 2.5–5 mol % of catalyst loadings, isolating the corresponding sulfoxides in good to excellent yields (75–93%) and high selectivity.     

Efficient dehydrative C-N bond formation using alcohols and amides in the presence of silica supported perchloric acid as a heterogeneous catalyst

Silica supported perchloric acid has been utilized as an efficient heterogeneous recyclable catalyst for N-alkylation of amides (sulfonamides and carboxamides) using alcohols (primary and secondary aliphatic as well as benzylic). The products are formed in high yields within 2-3 h.     

Synthesis of novel lipophilic and/or fluorophilic ethers of perfluoro-tert-butyl alcohol, perfluoropinacol and hexafluoroacetone hydrate via a Mitsunobu reaction: Typical cases of ideal product separation

Fluorophilic ethers having the structure RC(CF₃)₂O(CH₂)₃C_nF_2n + 1 are obtained in high yields, when F-tert-butyl alcohol (R = CF₃), F-acetone hydrate (R = O(CH₂)₃C_nF_2n + 1), F-pinacol (R = C(CF₃)₂O(CH₂)₃C_nF_2n + 1) are reacted with 3-perfluoroalkyl-1-propanols (C_nF_2n + 1(CH₂)₃OH, n = 4, 6, 8, 10) in a Mitsunobu reaction (Ph₃P/DIAD [i-PrO₂CN = NCO₂Pr-i]/ether). The parent lipophilic ethers with the structure of (CF₃)₃CO(CH₂)₃C_nH_2n + 1 were prepared analogously using the corresponding fatty alcohols and F-tert-butyl alcohol. To achieve ideal separations, products were transferred to orthogonal phases relative to the other reaction components using fluorous extraction, fluorous solid-organic liquid filtration, or steam-distillation. Selected physical properties including melting and boiling point, together with fluorous partition coefficients of these ethers were determined and the figures obtained were qualitatively analyzed using relevant thermodynamic theories. Some of these ethers are liquids with rather low freezing points and are miscible with fluorocarbon solvents.