- Cp*Ir complex-catalyzed N-heterocyclization of primary amines with diols: A new catalytic system for environmentally benign synthesis of cyclic amines
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(Chemical Equation Presented) A new efficient method for the N-heterocyclization of primary amines with diols catalyzed by a Cp*Ir complex was developed. A variety of five-, six-, and seven-membered cyclic amines were synthesized in good to excellent yields with the formation of only water as a byproduct. A two-step asymmetric synthesis of (S)-2-phenylpiperidine was also achieved using (R)-1-phenylethylamine as a starting primary amine.
- Fujita, Ken-Ichi,Fujii, Takeshi,Yamaguchi, Ryohei
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- Arene-catalysed reductive lithiation of tetrahydrofuran: Improved synthesis of 1,5-diols
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The reductive cleavage of tetrahydrofuran at -78°C can be easily achieved by using an excess of lithium powder in the presence of BF3-·OEt2 and a catalytic amount (8%) of an arene (naphthalene, biphenyl, 4,4'-di-tert-butylbiphenyl or anthracene), the best results being obtained with naphthalene. The dianion prepared by this method reacts with carbonyl compounds yielding 1,5-diols.
- Ramon,Yus
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Read Online
- Copper-mediated displacements of allylic THP ethers on a bisphosphonate template
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The copper-mediated displacement of allylic THP ethers by Grignard reagents has been examined in a system that contains a geminal bisphosphonate ester. With Grignard reagents derived from several aromatic halides or benzyl bromide the displacement proceed
- Shull, Larry W.,Wiemer, David F.
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- Nickel-Catalyzed Decarboxylative Coupling of Redox-Active Esters with Aliphatic Aldehydes
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The addition of alkyl fragments to aliphatic aldehydes is a highly desirable transformation for fragment couplings, yet existing methods come with operational challenges related to the basicity and instability of the nucleophilic reagents commonly employed. We report herein that nickel catalysis using a readily available bioxazoline (BiOx) ligand can catalyze the reductive coupling of redox-active esters with aliphatic aldehydes using zinc metal as the reducing agent to deliver silyl-protected secondary alcohols. This protocol is operationally simple, proceeds under mild conditions, and tolerates a variety of functional groups. Initial mechanistic studies suggest a radical chain pathway. Additionally, alkyl tosylates and epoxides are suitable alkyl precursors to this transformation providing a versatile suite of catalytic reactions for the functionalization of aliphatic aldehydes.
- Xiao, Jichao,Li, Zhenning,Montgomery, John
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supporting information
p. 21234 - 21240
(2021/12/27)
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- A phosphine-free iron complex-catalyzed synthesis of cycloalkanes: Via the borrowing hydrogen strategy
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Herein we report a diaminocyclopentadienone iron tricarbonyl complex catalyzed synthesis of substituted cyclopentane, cyclohexane and cycloheptane compounds using the borrowing hydrogen strategy in the presence of various substituted primary and secondary 1,n diols as alkylating reagents. Deuterium labeling experiments confirm that the diols were the hydride source in this cascade process. This journal is
- Bettoni, Léo,Gaillard, Sylvain,Renaud, Jean-Luc
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supporting information
p. 12909 - 12912
(2020/11/07)
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- Stereoselective synthesis of alicyclic ketones: A hydrogen borrowing approach
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A highly diastereoselective annulation strategy for the synthesis of alicyclic ketones from diols and pentamethylacetophenone is described. This process is mediated by a commercially available iridium(III) catalyst, and provides efficient access to a wide range of cyclopentane and cyclohexane products with high levels of stereoselectivity. The origins of diastereoselectivity in the annulation reaction have been explored by a series of control experiments, which provides an explanation for how each stereocentre around the newly forged ring is controlled.
- Armstrong, Roly J.,Akhtar, Wasim M.,Frost, James R.,Christensen, Kirsten E.,Stevenson, Neil G.,Donohoe, Timothy J.
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supporting information
(2019/11/13)
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- Aryl Boronic Acid Catalysed Dehydrative Substitution of Benzylic Alcohols for C?O Bond Formation
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A combination of pentafluorophenylboronic acid and oxalic acid catalyses the dehydrative substitution of benzylic alcohols with a second alcohol to form new C?O bonds. This method has been applied to the intermolecular substitution of benzylic alcohols to form symmetrical ethers, intramolecular cyclisations of diols to form aryl-substituted tetrahydrofuran and tetrahydropyran derivatives, and intermolecular crossed-etherification reactions between two different alcohols. Mechanistic control experiments have identified a potential catalytic intermediate formed between the aryl boronic acid and oxalic acid.
- Estopi?á-Durán, Susana,Donnelly, Liam J.,Mclean, Euan B.,Hockin, Bryony M.,Slawin, Alexandra M. Z.,Taylor, James E.
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supporting information
p. 3950 - 3956
(2019/02/16)
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- Visible-Light-Induced C-O Bond Formation for the Construction of Five- and Six-Membered Cyclic Ethers and Lactones
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Visible-light-induced intramolecular C-O bond formation was developed using 2,4,6-triphenylpyrylium tetrafluoroborate (TPT), which allows the regiocontrolled construction of cyclic ethers and lactones. The reaction is likely to proceed through the single-electron oxidation of the phenyl group, followed by the formation of a benzylic radical, thus preventing a competing 1,5-hydrogen abstraction pathway. Detailed mechanistic studies suggest that molecular oxygen is used to trap the radical intermediate to form benzyl alcohol, which undergoes cyclization. This new approach serves as a powerful platform by providing efficient access to valuable five- and six-membered cyclic ethers and lactones with a unified protocol.
- Im, Honggu,Kang, Dahye,Choi, Soyeon,Shin, Sanghoon,Hong, Sungwoo
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supporting information
p. 7437 - 7441
(2018/11/27)
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- Stereoselective Synthesis of Cyclohexanes via an Iridium Catalyzed (5 + 1) Annulation Strategy
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An iridium catalyzed method for the synthesis of functionalized cyclohexanes from methyl ketones and 1,5-diols is described. This process operates by two sequential hydrogen borrowing reactions, providing direct access to multisubstituted cyclic products with high levels of stereocontrol. This methodology represents a novel (5 + 1) strategy for the stereoselective construction of the cyclohexane core.
- Akhtar, Wasim M.,Armstrong, Roly J.,Frost, James R.,Stevenson, Neil G.,Donohoe, Timothy J.
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supporting information
p. 11916 - 11920
(2018/09/27)
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- Ketyl-type radicals from cyclic and acyclic esters are stabilized by SmI2(H2O)n: the role of SmI2(H 2O)n in post-electron transfer steps
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Mechanistic details pertaining to the SmI2-H2O- mediated reduction and reductive coupling of 6-membered lactones, the first class of simple unactivated carboxylic acid derivatives that had long been thought to lie outside the reducing range of SmI2, have been elucidated. Our results provide new experimental evidence that water enables the productive electron transfer from Sm(II) by stabilization of the radical anion intermediate rather than by solely promoting the first electron transfer as originally proposed. Notably, these studies suggest that all reactions involving the generation of ketyl-type radicals with SmI2 occur under a unified mechanism based on the thermodynamic control of the second electron transfer step, thus providing a blueprint for the development of a broad range of novel chemoselective transformations via open-shell electron pathways.
- Szostak, Michal,Spain, Malcolm,Procter, David J.
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supporting information
p. 8459 - 8466
(2014/06/24)
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- Synthesis of oxacyclic scaffolds via dual ruthenium hydride/Bronsted acid-catalyzed isomerization/cyclization of allylic ethers
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A ruthenium hydride/Bronsted acid-catalyzed tandem sequence is reported for the synthesis of 1,3,4,9-tetrahydropyrano[3,4-b]indoles (THPIs) and related oxacyclic scaffolds. The process was designed on the premise that readily available allylic ethers would undergo sequential isomerization, first to enol ethers (Ru catalysis), then to oxocarbenium ions (Bronsted acid catalysis) amenable to endo cyclization with tethered nucleophiles. This methodology provides not only an attractive alternative to the traditional oxa-Pictet-Spengler reaction for the synthesis of THPIs, but also convenient access to THPI congeners and other important oxacycles such as acetals.
- Ascic, Erhad,Ohm, Ragnhild G.,Petersen, Rico,Hansen, Mette R.,Hansen, Casper L.,Madsen, Daniel,Tanner, David,Nielsen, Thomas E.
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supporting information
p. 3297 - 3300
(2014/04/03)
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- Selective synthesis of unsymmetrical ethers from different alcohols catalyzed by sodium bisulfite
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An efficient method for the preparation of unsymmetrical ethers from alcohols catalyzed by sodium bisulfite is reported. The procedure enables the direct dehydration of primary, secondary, and tertiary benzylic alcohols with aliphatic alcohols in the abse
- Yu, Jun-Lai,Wang, Hui,Zou, Kai-Feng,Zhang, Jia-Rui,Gao, Xiang,Zhang, Dan-Wei,Li, Zhan-Ting
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supporting information
p. 310 - 315
(2013/01/15)
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- From diols to lactones under aerobic conditions using a laccase/TEMPO catalytic system in aqueous medium
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An efficient catalytic system to oxidize quantitatively aliphatic diols using Trametes versicolor laccase and TEMPO has been developed in aqueous medium. Oxidations have occurred in a non-stereoselective fashion but with complete regio- and/or monoselectivity, obtaining lactones with excellent purity after simple extraction. This catalytic system has been demonstrated to be scalable, compatible with the presence of a variety of functionalities, and also allowed the successful enzyme recycling using a laccase-cross-linked enzyme aggregates (CLEA) preparation.
- Gotor-Fernandez, Vicente,Diaz-Rodriguez, Alba,Lavandera, Ivan,Kanbak-Aksu, Seda,Sheldon, Roger A.,Gotor, Vicente
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supporting information
p. 3405 - 3408
(2013/02/22)
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- Highly practical copper(I)/TEMPO catalyst system for chemoselective aerobic oxidation of primary alcohols
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Aerobic oxidation reactions have been the focus of considerable attention, but their use in mainstream organic chemistry has been constrained by limitations in their synthetic scope and by practical factors, such as the use of pure O2 as the oxidant or complex catalyst synthesis. Here, we report a new (bpy)CuI/TEMPO catalyst system that enables efficient and selective aerobic oxidation of a broad range of primary alcohols, including allylic, benzylic, and aliphatic derivatives, to the corresponding aldehydes using readily available reagents, at room temperature with ambient air as the oxidant. The catalyst system is compatible with a wide range of functional groups and the high selectivity for 1° alcohols enables selective oxidation of diols that lack protecting groups.
- Hoover, Jessica M.,Stahl, Shannon S.
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supporting information; experimental part
p. 16901 - 16910
(2011/12/04)
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- Reduction of aromatic and aliphatic keto esters using sodium borohydride/MeOH at room temperature: a thorough investigation
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Reduction of keto esters is a valuable alternative to produce diols. Sodium borohydride/MeOH system at room temperature and short reaction time efficiently reduced α, β, γ, and δ-keto esters having α-keto esters as the most reactive. The ester functionality was reduced effectively due to the presence of oxo group that somehow facilitates the formation of ring intermediate. As expected, the chemoselective experiments showed that ester functionality was not reduced using this system. This study presents a simple, easy, and benign reduction process of various keto esters to its corresponding diols.
- Kim, Juryoung,De Castro, Kathlia A.,Lim, Minkyung,Rhee, Hakjune
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supporting information; experimental part
p. 3995 - 4001
(2010/07/05)
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- Gold-catalysed cyclic ether formation from diols
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Gold(I) and (III) salts have been found to be highly effective at the catalysis of ether formation from alcohols. Intramolecular ether formation of a 1,5-diol was also achieved, with a stereoselectivity that indicates that an SN1 mechanism predominates. In an attempt to form a seven-membered ring, a stable 14-membered dimer product was also formed. Attempts to control the diastereoselectivity of the reaction using a chiral anionic counterion did not give products with a high de.
- Jiang, Xiaolu,London, Emma K.,Morris, David J.,Clarkson, Guy J.,Wills, Martin
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experimental part
p. 9828 - 9834
(2011/02/23)
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- ANGIOTENSIN II RECEPTOR ANTAGONISTS
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A compound having the structure (I) wherein R is an angiotensin receptor antagonist active group, Y is selected from the group consisting of (II), and 2) -C(R1H)OC(O)X((CR12R13)-(CHR10)m-(CH2)n-Zp-(CH
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Page/Page column 29
(2009/09/05)
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- TBD-catalyzed direct 5- and 6-enolexo aldolization of ketoaldehydes
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Treatment of unfunctionalized acyclic ketoaldehydes with a catalytic amount of 1,5,7-triazabicyclo[4.4.0]dec-5-ene induces a direct intramolecular 5- and 6-enolexo aldolization, furnishing 2-ketocyclopentanols and 2-ketocyclohexanols in good-to-excellent yields. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Ghobril, Cynthia,Sabot, Cyrille,Mioskowski, Charles,Baati, Rachid
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supporting information; experimental part
p. 4104 - 4108
(2009/05/27)
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- Selective synthesis of secondary and tertiary amines by Cp*iridium-catalyzed multialkylation of ammonium salts with alcohols
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(Chemical Equation Presented) The efficient selective synthesis of secondary and tertiary amines has been achieved by means of Cp*Ir- catalyzed multialkylation of ammonium salts with alcohols without solvent: the reactions of ammonium acetate with alcohols gave tertiary amines exclusively, while those of ammonium tetrafluoroborate afforded secondary amines selectively. Using this method, secondary 5- and 6-membered cyclic amines were synthesized from ammonium tetrafluoroborate and diols in one pot.
- Yamaguchi, Ryohei,Kawagoe, Shoko,Asai, Chiho,Fujita, Ken-Ichi
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p. 181 - 184
(2008/09/18)
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- Samarium diiodide-induced intramolecular pinacol coupling of dinitrones: Synthesis of cyclic cis-vicinal diamines
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Pinacol coupling of alkyl dinitrones mediated by SmI2 was achieved in the presence of a proton source allowing the synthesis of cyclic vicinal diamines with good cis-selectivity. The Royal Society of Chemistry 2005.
- Ebran, Jean-Philippe,Hazell, Rita G.,Skrydstrup, Troels
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p. 5402 - 5404
(2007/10/03)
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- Selective oxidation of alcohols at the benzylic position by benzeneseleninic anhydride
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Benzeneseleninic anhydride in the presence of tert-butyl hydroperoxide in chlorobenzene at about 70°C is an effective oxidizing agent for the selective oxidation of alcohols at the benzylic position.
- Toki, Naotoshi,Satoh, Tsuyoshi
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p. 1009 - 1012
(2007/10/03)
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- Application of a one-pot lipase resolution strategy for the synthesis of chiral γ- and δ-lactones
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A successful one-pot reduction of γ-ketoesters, δ-ketoesters and lactones to the corresponding 1,4- and 1,5-diols followed by a lipase catalyzed kinetic resolution coupled with hydrolysis to afford optically active diols is described. The synthetic utility of this one-pot method was illustrated by the oxidation of these chiral diols to respective chiral γ-butyrolactone and δ-lactones. Lipase from Pseudomonas cepacia, immobilized on ceramic afforded the product with high enantiomeric excess in good yields under mild reaction conditions. This approach has been used to develop a convenient enantioselective route for several γ- and δ-lactones using achiral and corresponding racemic starting material.
- Kamal, Ahmed,Sandbhor, Mahendra,Shaik, Ahmad Ali
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p. 1575 - 1580
(2007/10/03)
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- Inter- and intramolecular pathways for the formation of tetrahydrofurans from β-(phosphatoxy)alkyl radicals. Evidence for a dissociative mechanism
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β-(Phosphatoxy)alkyl radicals generated by photolysis of Barton PTOC esters in the presence of allyl alcohol and tert-butyl mercaptan undergo nucleophilic substitution followed by 5-exo-trig radical ring closure leading to tetrahydrofurans in good yield and with high trans selectivity. β- (Phosphatoxy)alkyl radicals obtained by intramolecular hydrogen 1,5- abstraction with an alkoxyl radical undergo nucleophilic displacement providing tetrahydrofurans. The ensemble of results, including the effects of leaving groups and substituents, strongly support a dissociative mechanism for these radical nucleophilic displacement reactions.
- Crich, David,Huang, Xianhai,Newcomb, Martin
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p. 523 - 529
(2007/10/03)
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- Synthesis of benzanilide derivatives as dual acting agents with α1- adrenoceptor antagonistic action and steroid 5-α reductase inhibitory activity
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Synthesis of benzanilide derivatives which have dual α1-adrenoceptor antagonistic action and steroid 5α-reductase inhibitory activity and their structure-activity relationships is described.
- Yoshida, Kiyoshi,Horikoshi, Yoichiro,Eta, Masaaki,Chikazawa, Jun,Ogishima, Masayuki,Fukuda, Yohichi,Sato, Hiroki
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p. 2967 - 2972
(2007/10/03)
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- Chemoselective reduction of β-keto-esters to β-keto-alcohols
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Chemoselective reduction of the ester group in keto-esters was studied.Treatment of potassium (or lithium) enolate anions of β-keto-esters with aluminium hydride reduced the ester group chemoselectvely to give β-keto-alcohols in moderate yield.Similar reactions of γ- and δ-keto-esters were not chemoselective, yielding a mixture of the diol and the keto-alcohol.Keywords - chemoselective reduction; aluminium hydride; β-keto-ester; β-keto-alcohol; potassium hydride; enolate anion.
- Isobe, Kimiaki,Mohri, Kunihiko,Sano, Hiromichi,Taga, Juni-ichi,Tsuda, Yoshisuke
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p. 3029 - 3032
(2007/10/02)
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- SILAFUNCTIONAL COMPOUNDS IN ORGANIC SYNTHESIS. 30. INTRAMOLECULAR HYDROSILATION OF ALKENYL ALCOHOLS: A NEW APPROACH TO THE REGIOSELECTIVE SYNTHESIS OF 1,2- AND 1,3-DIOLS
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Intramolecular hydrosilation of allyl and homoallyl alcohols and the subsequent oxidative cleavage of the resultant carbon-silicon bond have provided a new approach to the regio-controlled synthesis of 1,2- and/or 1,3-diols.
- Tamao, Kohei,Tanaka, Tetsu,Nakajima, Takashi,Sumiya, Ritsuo,Arai, Hitoshi,Ito, Yoshihiko
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p. 3377 - 3380
(2007/10/02)
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