601-53-6Relevant articles and documents
Reduction of a Δ4-steroid with diborane
D'Alessandro,Giacopello,Seldes,Deluca
, p. 2703 - 2708 (1995)
Reported here is a boron process equivalent to stereoselective olefin reduction and concomitant protecting group cleavage.
Acceptorless Dehydrogenation of N-Heterocycles and Secondary Alcohols by Ru(II)-NNC Complexes Bearing a Pyrazoyl-indolyl-pyridine Ligand
Wang, Qingfu,Chai, Huining,Yu, Zhengkun
, p. 584 - 591 (2018/03/08)
Ruthenium(II) hydride complexes bearing a pyrazolyl-(2-indol-1-yl)-pyridine ligand were synthesized and structurally characterized by NMR analysis and X-ray single crystal crystallographic determinations. These complexes efficiently catalyzed acceptorless dehydrogenation of N-heterocycles and secondary alcohols, respectively, exhibiting highly catalytic activity with a broad substrate scope. The present work has established a strategy to construct highly active transition metal complex catalysts and provides an atom-economical and environmentally benign protocol for the synthesis of aromatic N-heterocyclic compounds and ketones.
Iron-Catalyzed Chemoselective Reduction of α,β-Unsaturated Ketones
Lator, Alexis,Gaillard, Sylvain,Poater, Albert,Renaud, Jean-Luc
supporting information, p. 5770 - 5774 (2018/03/26)
An iron-catalyzed chemo- and diastereoselective reduction of α,β-unsaturated ketones into the corresponding saturated ketones in mild reaction conditions is reported herein. DFT calculations and experimental work underline that transfer hydride reduction is a more facile process than hydrogenation, unveiling the fundamental role of the base.
Regioselective dehydrogenation of 3-keto-steroids to form conjugated enones using o-iodoxybenzoic acid and trifluoroacetic acid catalysis
Iida, Takashi,Omura, Kaoru,Sakiyama, Ryou,Kodomari, Mitsuo
, p. 45 - 51 (2014/03/21)
Mild and regioselective conversion of 3-keto-5α- and 3-keto-5β-steroids (trans A/B- and cis A/B-ring juncture, respectively) to the corresponding enones (Δ1- and Δ4-3- ketones) by treatment with o-iodoxybenzoic acid (IBX) catalyzed by trifluoroacetic acid (TFA) in DMSO, is described. The IBX-mediated reaction involved dehydrogenation of the α- and β-hydrogen atoms of the 3-ketones to give the enones regioselectively in good isolated yields without concomitant formation of related dienones and trienones.
Direct organocatalytic stereoselective transfer hydrogenation of conjugated olefins of steroids
Ramachary, Dhevalapally B.,Sakthidevi, Rajasekar,Reddy, P. Srinivasa
, p. 13497 - 13506 (2013/09/02)
Kinetically controlled and organocatalytic syn-selective transfer hydrogenation has been successfully demonstrated for the reduction of the enone functional group of various steroids. Herein, diastereoselective synthesis of many 5β-steroids have been reported through organocatalysis, which have broad medicinal and pharmaceutical applications. The mechanistic studies and the selectivity of the products clearly indicated that the catalyst 1b·d-CSA is mild enough to activate the various chiral cyclic enones through iminium ion formation during the organocatalytic transfer hydrogenations with Hantzsch ester 2a as a hydrogen source. Further, clear evidence for the selective formation of intermediate iminium species [I]+ have been characterized through on-line monitoring of controlled experiments by NMR and ESI-HRMS analyses.
Substrate analog studies of the ω-regiospecificity of Mycobacterium tuberculosis cholesterol metabolizing cytochrome P450 enzymes CYP124A1, CYP125A1 and CYP142A1
Johnston, Jonathan B.,Singh, Arti A.,Clary, Anaelle A.,Chen, Chiung-Kuan,Hayes, Patricia Y.,Chow, Sharon,De Voss, James J.,Ortiz De Montellano, Paul R.
experimental part, p. 4064 - 4081 (2012/09/22)
We report the synthesis and evaluation of a series of cholesterol side-chain analogs as mechanistic probes of three important Mycobacterium tuberculosis cytochrome P450 enzymes that selectively oxidize the ω-position of the methyl-branched cholesterol side-chain. To probe the structural requirements for the thermodynamically disfavored ω-regiospecificity we compared the binding of these substrate analogs to each P450, determined the turnover rates, and characterized the enzymatic products. The results are discussed in the context of the structure-activity relationships of the enzymes and how their active sites enforce ω-oxidation.
Twist does a twist to the reactivity: Stoichiometric and catalytic oxidations with twisted tetramethyl-IBX
Moorthy, Jarugu Narasimha,Senapati, Kalyan,Parida, Keshaba Nanda,Jhulki, Samik,Sooraj, Kunnikuruvan,Nair, Nisanth N.
experimental part, p. 9593 - 9601 (2012/01/03)
The methyl groups in TetMe-IBX lower the activation energy corresponding to the rate-determining hypervalent twisting (theoretical calculations), and the steric relay between successive methyl groups twists the structure, which manifests in significant solubility in common organic solvents. Consequently, oxidations of alcohols and sulfides occur at room temperature in common organic solvents. In situ generation of the reactive TetMe-IBX from its precursor iodo-acid, i.e., 3,4,5,6-tetramethyl-2-iodobenzoic acid, in the presence of oxone as a co-oxidant facilitates the oxidation of diverse alcohols at room temperature.
One-Pot Bi(OTf)catalyzed oxidative deprotection of tert -butyldimethyl silyl ethers with TEMPO and co-oxidants
Barnych, Bogdan,Vatèle, Jean-Michel
experimental part, p. 2048 - 2052 (2011/10/19)
A sequential one-pot synthesis for the oxidation of primary and secondary tert-butyldimethylsilyl (TBDMS) ethers, using catalytic amounts of metal triflates and TEMPO in combination with PhIO or PhI(OAc)in THF or acetonitrile, is described. Acid-sensitive protecting groups such as methylidene, isopropylidene, acetals, and Boc are unaffected under the reaction conditions. Another feature of this procedure is its high selectivity for TBDMS ethers over tert-butyldiphenylsilyl ethers and of aliphatic TBDMS groups over phenolic TBDMS groups. Georg Thieme Verlag Stuttgart - New York.
Application of the excited state meta effect in photolabile protecting group design
Wang, Pengfei,Hu, Ayou,Wang, Yun
, p. 2831 - 2833 (2008/02/07)
A novel photolabile protecting group for carbonyl compounds has been developed, based on the excited state meta effect.
Ammonium formate/palladium on carbon: A versatile system for catalytic hydrogen transfer reductions of carbon-carbon double bonds
Paryzek, Zdzislaw,Koenig, Hanna,Tabaczka, Bartlomiej
, p. 2023 - 2026 (2007/10/03)
Various carbon-carbon double bonds in olefins and α,β -unsaturated ketones were effectively reduced to the corresponding alkanes and saturated ketones, using ammonium formate as a hydrogen transfer agent in the presence of Pd/C as catalyst in refluxing methanol.
