105-30-6Relevant articles and documents
Hydroboration. 77. Revision of the Regioselectivity of the Hydroboration of Alkenes with Dihaloborane-Dimethyl Sulfide Complexes
Brown, Herbert C.,Racherla, Uday S.
, p. 895 - 897 (1986)
The hydroboration of alkanes with dihaloborane-dimethyl sulfide complexes (HBX2*SMe2, X = Cl, Br, and I) was systematically reexamined to establish the true regioselectivities in hydroboration with these reagents.Hydrogen halides (HX, X = Cl, Br, and I) liberated during the hydrolysis-oxidation of the alkyldihaloborane-dimethyl sulfide complexes (RBX2*SMe2) add to the residual alkene and hydrolyze to alcohols, thus introducing a significant error in the regioselectivity of such hydroborations.The true regioselectivities in the hydroboration of alkenes with HBX2*SMe2 reveal considerably smaller formation of secondary and tertiary derivatives than previously reported, a result that should significantly enhance the value of these hydroborating agents.
Enantioselective Synthesis of the Proposed Structure of Santinol D
Xiong, Xin,Wu, Yikang,Liu, Bo
, p. 948 - 960 (2020)
In connection with structural verification of santinol D, a unique tricylglycerol isolated from Helichrysum italicum subsp. microphyllum, four possible isomers of its C-2'''and C-4''' centers were synthesized. The two enolizable chiral centers were installed with pre-defined absolute configurations using Evans alkylation and aldol condensation, respectively. The extra chiral center introduced in the aldol condensation was removed by Dess–Martin oxidation to convert the adjacent methine group into the highly enolizable subunit of an α-alkyl-β-keto ester at the end of the synthesis. The synthetic isomers provided unequivocal physical and NMR data for every single enantiomer and thus provided the information required for the configurational assignment of this natural product. With the aid of a model compound, the racemization of such species was examined polarimetrically under several sets of typical conditions and the rates were also calculated from the corresponding kinetics data.
ORGANOBORANES FOR SYNTHESIS. 5. STOICHIOMETRICALLY CONTROLLED REACTION OF ORGANOBORANES WITH OXYGEN UNDER MILD CONDITIONS TO ACHIEVE QUANTITATIVE CONVERSION TO ALCOHOLS
Brown, Herbert C.,Midland, M. Mark,Kabalka, George W.
, p. 5523 - 5530 (1986)
The reaction of organoboranes with oxygen under mild conditions can be controlled to give an essentially quantitative conversion of all three alkyl groups on boron to the corresponding alcohol.The controlled oxidation is a very clean reaction, with only minor amounts of carbonyl and hydrocarbon products formed.All organoboranes react quite rapidly in the initial stages, but vary considerably in the time required to achieve the desired uptake of oxygen.In contrast to oxidation by alkaline hydrogen peroxide, a portion of this reaction proceeds through alkyl radicals, thus resulting in some loss of stereospecificity.Oxidation of mixed organoboranes reveals that the relative rates of oxidation of alkyl groups on boron are consistent with a radical mechanism, with tertiary > secondary > primary in the rate of oxidation.The selective oxidation of one alkyl group in the presence of the other is not possible, due to small differences in relative rates of oxidation.However, thexyl and cyclohexyl groups can be selectively removed from boron in the presence of alkenyl groups.Thus, controlled oxidation of thexyldialkenylborane affords pure dialkenylborinic acid.
ORGANOBORANES FOR SYNTHESIS. 6. A CONVENIENT, GENERAL SYNTHESIS OF ALKYLHYDROPEROXIDES via AUTOXIDATION OF ORGANOBORANES
Brown, Herbert C.,Midland, M. Mark
, p. 4059 - 4070 (1987)
The low temperature autoxidation of organoboranes in tetrahydrofuran leads to the formation of diperoxyboranes, which provide the corresponding alkylhydroperoxides in excellent yields, upon treatment with hydrogen peroxide.However, only two of the three alkyl groups on boron are used for the formation of hydroperoxides.This difficulty was solved by employing alkyldichloroborane etherates instead of trialkylboranes.The alkyldichloroborane etherates react cleanly with one molar equivalent of oxygen in ether solvent.The product is readily hydrolyzed to form the corresponding hydroperoxides in excellent yields.The autoxidation of organoboranes is inhibited by iodine or such free-radical scavengers.A study of the inhibition by iodine of the oxidation of representative trialkylboranes indicates that the rate of initiation decreases with an increase in the steric crowding about the boron atom.The rate of inhibition of the autoxidation of trialkylboranes by iodine reveals that the reaction involves a relatively slow rate of radical initiation, followed by a very fast rate of chain propagation.
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Brown,Ravindran
, p. 695 (1977)
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Cp2TiCl2-catalyzed grignard reactions. 2. Reactions with ketones and aldehydes
Sato, Fumie,Jinbo, Takamasa,Sato, Masao
, p. 2171 - 2174 (1980)
The reaction of Grignard reagents with ketones or aldehydes in the presence of a catalytic amount of Cp2TiCl2 leads to the corresponding reduction products in high yields. Cp2TiH intermediate was proposed to account for this observation.
Synthesis and fungicidal activity of 2-methylalkyl isonicotinates and nicotinates
Huras, Bogumi?a,Zakrzewski, Jerzy,Krawczyk, Maria,Bombińska, Danuta,Cieniecka-Ros?onkiewicz, Anna,Michalczyk, Alicja
, p. 509 - 517 (2017)
Abstract: Homologs and analogs of 2-methylheptyl isonicotinate (new, natural antifungal and antibacterial antibiotic isolated from Streptomyces sp. 201): racemic 2-methylalkyl isonicotinates 4 and nicotinates 5 and enantiomerically enriched in the R and S isomers, 2-methylpentyl isonicotinate and nicotinate were obtained. Fungistatic activity of the compounds was evaluated. Nicotinates 5a–c show significant activity against phytopathogenic fungi: Fusarium culmorum, Phytophthora cactorum, Rhizoctonia solani. The activity of the enantiomerically enriched compounds was comparable to the activity of racemic ones. There was no significant difference in fungistatic activity between the enantiomerically enriched R and S isomers. Investigated compounds and their oxalates have proven to be active against chalkbrood disease caused by fungal species Ascosphaera apis. The activity of the nicotinates 5a and 5b and oxalates 5a–c against Ascosphaera apis was higher than the activity of oxalic acid itself. Especially high activity was shown for 2-methylbutyl nicotinate 5a and oxalate of 2-methylpentyl nicotinate 5b. Graphical abstract: [InlineMediaObject not available: see fulltext.]
SODIUM PERCARBONATE: A CONVENIENT REAGENT FOR EFFICIENTLY OXIDIZING ORGANOBORANES
Kabalka, George W.,Wadgaonkar, Prakash P.,Shoup, Timothy M.
, p. 5103 - 5104 (1989)
Sodium percarbonate, a readily available, inexpensive and easy to handle reagent, efficiently oxidizes organoboranes.The yields of alcohols are essentially identical to those obtained using standard oxidation procedure.
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Brown,H.C. et al.
, p. 2417 - 2422 (1979)
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Felkin,H. et al.
, p. 707 - 710 (1969)
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Reaction network of aldehyde hydrogenation over sulfided Ni-Mo/Al 2O3 catalysts
Wang, Xueqin,Saleh, Ramzi Y.,Ozkan, Umit S.
, p. 20 - 32 (2005)
A reaction network of aldehyde hydrogenation over NiMoS/Al 2O3 catalysts was studied with aldehydes with straight and branched carbon chains and different chain lengths as feed materials. The reactions in the gas phase and the liquid phase were compared. The main reaction in the aldehyde hydrogenation process is the hydrogenation of the CO double bond, which takes place over the coordinatively unsaturated sites. The major side reactions are self-condensation of aldehydes and condensation of aldehydes with alcohols. Both reactions involve α-hydrogen and are primarily catalyzed by acid-base bifunctional sites over the exposed Al2O 3 surfaces.
Etherification of aldehydes, alcohols and their mixtures on Pd/SiO2 catalysts
Pham, Trung T.,Crossley, Steven. P.,Sooknoi, Tawan,Lobban, Lance L.,Resasco, Daniel E.,Mallinson, Richard G.
, p. 135 - 140 (2010)
Dialkyl ethers have been selectively produced from etherification of aldehydes and alcohols on supported Pd catalysts. A yield of 79% ether with a selectivity of 90% was observed when feeding 2-methylpentanal with 2-methylpentanol at a molar ratio 1:1 at 125 °C. Cross etherification of n-butanol with 2-methylpentanal shows a much higher rate than that observed when the alcohol or aldehyde is fed alone. This enhanced activity is in line with the catalyst requirement for large ensembles that allow surface alkoxide species next to η2 adsorbed aldehydes. Etherification when only aldehyde or alcohol is fed arises predominantly due to aldehyde-alcohol inter-conversion to produce the necessary co-reactant. The ether yield at the same reaction conditions decreases with metal loading in the order 16 > 10 > 3 wt.% Pd. Increasing reduction temperature also increases ether yield. It is apparent that etherification is highly sensitive to metal particle morphology, consistent with needing ensembles that accommodate the two adjacent adsorption sites.
Hotta,Kubomatsu
, p. 3118,3119-3120 (1972)
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Laine
, p. 6451 (1978)
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Asymmetric Oxidoreductions Catalyzed by Alcohol Dehydrogenase in Organic Solvents
Grunwald, Jacob,Wirz, Beat,Scollar, Mark P.,Klibanov, Alexander M.
, p. 6732 - 6734 (1986)
A methodology is developed for the use of alcohol dehydrogenase (and other NAD+/NADH-dependent enzymes) as catalysts in organic solvents.The enzyme and the cofactor are deposited onto the surface of glass beads which are then suspended in a water-immiscible organic solvent containing the substrate.Both NADH and NAD+ are efficiently regenerated in such a system with alcohol dehydrogenase-catalyzed oxidation of ethanol and reduction of isobutyraldehyde, respectively; cofactor turnover numbers of 1E5 to greater than 1E6 have been obtained.With use of asymmetric oxidoreductions catalyzed by horse liver alcohol dehydrogenase in isopropyl ether, optically active (ee of 95 to 100percent) alcohols and ketones have been prepared on a 1 to 10 mmol scale.
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Holliday,Polgar
, p. 2934 (1957)
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Bordenca,Marsico
, p. 1541 (1967)
Selective, base-free hydrogenation of aldehydes catalyzed by IR complexes based on proton-responsive lutidine-derived CNP ligands
álvarez, Eleuterio,Hernández-Juárez, Martín,López-Serrano, Joaquín,Paneque, Margarita,Rendón, Nuria,Sánchez, Práxedes,Suárez, Andrés
, p. 1314 - 1327 (2021/05/31)
Metal catalysts based on ligands containing proton-responsive sites have found widespread applications in the hydrogenation of polar unsaturated substrates. In this contribution, Ir complexes incorporating lutidine-derived CNP (C = N-heterocyclic carbene, NHC; P = phosphine) pincer ligands with two nonequivalent Br?nsted acid/base sites have been examined in the hydrogenation of aldehydes. To this end, Ir(CNP)H2Cl complexes were synthesized in two steps from the CNP ligand precursors and Ir(acac)(COD). These derivatives react with an excess of NaH to yield the trihydride derivatives Ir(CNP)H3, which were assessed as catalyst precursors in the hydrogenation of a series of aldehydes. The catalytic reactions were performed using commercial-grade substrates under neutral, mild conditions (0.1 mol % Ir-CNP; 4 bar H2, room temperature) with high conversions and selectivities for the reduction of the carbonyl function in the presence of other readily reducible groups such as C=C, nitro, and halogens. Reaction of an Ir(CNP)H2Cl complex with base in the presence of an aromatic aldehyde produces the reversible formation of alkoxide Ir complexes in which the aldehyde is bound to the deprotonated pincer framework (CNP*) through the CH-NHC arm of the ligand. These species, along with a carboxylate complex resulting from the Ir mediated oxidation of the aldehyde by water, is observed in the reaction of Ir(CNP)H3 with benzaldehyde. Finally, investigation of the mechanism of the hydrogenation of aldehydes has been carried out by means of DFT calculations considering the involvement of each arm of the Ir-CNP/CNP* derivatives. Calculations support a mechanism in which the catalyst switches its metal?ligand cooperation sites to follow the lowest energy pathway for each step of the catalytic cycle.
Iridium-Catalyzed Domino Hydroformylation/Hydrogenation of Olefins to Alcohols: Synergy of Two Ligands
Beller, Matthias,Huang, Weiheng,Jackstell, Ralf,Jiao, Haijun,Tian, Xinxin
supporting information, (2022/01/13)
A novel one-pot iridium-catalyzed domino hydroxymethylation of olefins, which relies on using two different ligands at the same time, is reported. DFT computation reveals different activities for the individual hydroformylation and hydrogenation steps in the presence of mono- and bidentate ligands. Whereas bidentate ligands have higher hydrogenation activity, monodentate ligands show higher hydroformylation activity. Accordingly, a catalyst system is introduced that uses dual ligands in the whole domino process. Control experiments show that the overall selectivity is kinetically controlled. Both computation and experiment explain the function of the two optimized ligands during the domino process.