14597-42-3Relevant articles and documents
N-indolyltriethylborate: A useful reagent for synthesis of C3-quaternary indolenines
Lin, Aijun,Yang, Jiong,Hashim, Mohamed
supporting information, p. 1950 - 1953 (2013/06/04)
N-Indolyltriethylborate was found to be a useful reagent for dearomatizing C3-alkylation of 3-substituted indoles with both activated and nonactivated alkyl halides to give C3-quaternary indolenines, pyrroloindolines, furoindoline, and hexahydropyridoindoline under mild reaction conditions. The utility of these reagents was demonstrated in the syntheses of a pyrroloindoline-4- cholestene hybrid and debromoflustramine B.
Oxidation of Δ4- and δ5-steroids with hydrogen peroxide catalyzed by porphyrin complexes of MnIII and FeIII
Rebelo, Susana L. H.,Simoes, Mario M. Q.,M. Graca P. M. S. Neves,Silva, Artur M. S.,Cavaleiro, Jose A. S.,Peixoto, Andreia F.,Pereira, Mariette M.,Silva, Manuela R.,Paixao, Jose A.,Beja, Ana M.
, p. 4778 - 4787 (2007/10/03)
In this paper we describe a new environmentally friendly method to promote the stereoselective epoxidation of Δ4- and Δ5- steroids. Metalloporphyrins efficiently catalyze the epoxidation reactions of 17β-acetoxy-4-androstene (1), 4-cholestene (2) and 3β-acetoxy-5- cholestene (3) in the presence of H2O2 as oxygen donor. Modeling the molecular structure of the porphyrin as well as the central metal allows the control of the preferential formation of α- or β-epoxides. Porphyrins with bulky, electron-withdrawing groups in the ortho positions of the meso phenyls and with MnIII as the central metal ion, such as [Mn(TDCPP)Cl], gave preferentially the β-epoxide of Δ4- and Δ5-steroids. [Fe(TPFPP)Cl] catalyzes preferentially the α-epoxidation of Δ4-steroids and also increases the stereoselectivity for the α-epoxide in Δ5-steroids, similar to the results obtained with m-CPBA (m-chloroperbenzoic acid) as oxidant. The substrate structure strongly influences the chemoselectivity of the reactions. The X-ray structures of two main products were determined, and two-dimensional NMR techniques allowed the full assignment of 1H and 13C NMR resonances as well as the stereochemistry of these products. A mechanistic proposal involving oxo species for the β-approach and peroxy species for the α-approach is proposed. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
Nitrous oxide oxidation catalyzed by ruthenium porphyrin complex
Tanaka, Hirotaka,Hashimoto, Kentaro,Suzuki, Kyosuke,Kitaichi, Yasunori,Sato, Mitsuo,Ikeno, Taketo,Yamada, Tohru
, p. 1905 - 1914 (2007/10/03)
Dinitrogen oxide was employed as a clean oxidant for various oxidations in the presence of a catalytic amount of dioxoruthenium tetramesitylporphyrin complex (Ru(tmp)(O)2). A variety of olefins, secondary alcohols, and benzyl alcohols were smoothly oxidized to the corresponding epoxides, ketones, and aldehydes in high yields. In the oxidation of 9,10-dihydroanthracene derivatives, the competitive reactions affording anthraquinones and anthracenes could be regulated by the reaction conditions. At a high temperature (200°C), anthraquinones were selectively produced, while the anthracenes were selectively produced by the addition of sulfuric acid.
Chemoselective Reduction of Complex α,β-Unsaturated Ketones to Allylic Alcohols over Ir-Metal Particles on β Zeolites
De Bruyn, Mario,Coman, Simona,Bota, Roxana,Parvulescu, Vasile I.,De Vos, Dirk E.,Jacobs, Pierre A.
, p. 5333 - 5336 (2007/10/03)
The combination of Ir, which has a strong affinity for carbonyl groups, with an acid H-β zeolite as a support and promotor, provides an effective catalyst for the chemoselective hydrogenation of α,β-unsaturated aldehydes and ketones to the corresponding allylic alcohols. Steroidal enones are suitable substrates for this transformation (see scheme). R = CH (Me)(CH2)3CH(Me)2.
Phosphine effects in the copper(I) hydride-catalyzed hydrogenation of ketones and regioselective 1,2-reduction of α,β-unsaturated ketones and aldehydes. Hydrogenation of decalin and steroidal ketones and enones
Chen, Jian-Xin,Daeuble, John F.,Stryker, Jeffrey M.
, p. 2789 - 2798 (2007/10/03)
The stereoselectivity and regioselectivity of the catalytic hydrogenation of ketones and α,β-unsaturated ketones and aldehydes using soluble copper(I) hydride catalysts have been investigated as a function of the ancillary phosphine ligand. While a relatively narrow range of aryldialkylphosphine ligands produce active hydrogenation catalysts, some ligands provide higher selectivity for 1,2-reduction of acyclic unsaturated carbonyl substrates than observed using the previously reported dimethylphenylphosphine-stabilized catalyst. The synthetic utility of this class of hydridic hydrogenation catalysts is illustrated by the hydrogenation of decalin and steroidal ketones and enones, the latter giving allylic alcohols with high selectivity. (C) 2000 Elsevier Science Ltd.
Reaktionen von Ph2SbH und p-TolSbH2 mit organischen Verbindungen
Breunig,Probst
, p. 297 - 303 (2007/10/03)
p-TolSbH2 reacts with styrene with formation of ethylbenzene and (p-TolSb)n (n=4, 5 in benzene). The action of phenyl acetylene on p-TolSbH2 gives styrene. Addition of Ph2SbH on phenyl acetylene in the presence of AIBN (azodiisobutyronitrile) yields 95% trans- and 5% cis-PhCH=CHSbPh2. Ph2SbH reacts with benzaldehyde in the presence of AIBN with formation of benzylalcohol (98%) and with various prochiral ketones in the presence of chiral auxiliares to give alcohols in high optical yields. Benzotrichloride reacts with Ph2SbH in the presence of PdCl2 to give benzylidene chloride. 1-Bromo adamantane, dibromo cholestanol, 2-chloro acetophenone, cinnamic acid chloride, and chloro acetophenone react with Ph2SbH/AIBN with substitution of the halogen atoms by hydrogen. Benzylbenzoate is formed the by action of Ph2SbH/AIBN on benzoyl chloride.
A Reinvestigation of the Meerwein-Ponndorf-Verley Reduction: A Highly Efficient Variation Using Zirconium Catalysts
Knauer, Birgit,Krohn, Karsten
, p. 677 - 684 (2007/10/02)
A new variation of the Meerwein-Ponndorf-Verley reduction based on mechanistic considerations is presented.Under optimized conditions 1-(4-dimethylaminophenyl)ethanol was used as the reducing alcohol (2-4 equiv.), Zr(O-tBu)4 as the catalyst (0.2 equiv.), and toluene or cyclohexane as the solvent.Aldehydes and ketones (if not extremely sterically hindered) were reduced to the corresponding alcohols at room temperature mostly within 2-4 h in essentially quantitative yield. α,β-Unsaturated carbonyl compounds cleanly react in a 1,2-mode to afford the corresponding allylic alcohols. - Key Words: Reductions / Meerwein-Ponndorf-Verley reaction / Catalysis / Zirconium tetra-tert-butoxide / β-Hydride shift / Kinetics
Cadmium Chloride-Magnesium-Water: A New System For Reduction of Various Organic Functionalities
Bordoloi, Manobjyoti
, p. 1681 - 1684 (2007/10/02)
Cadmium chloride-magnesium-THF-water efficiently reduced aldehydes and ketones to their corresponding alcohols, epoxide to mono-alcohol, benzyl halide to toluene, acid chloride to aldehyde and hydrolyzed thioketals to corresponding ketones. Key words: Cadmium chloride-magnesium-THF-H2O, reductions.
