- Nitrosotetrazolium-Catalyzed Aerobic Oxidation of Alcohols to the Corresponding Carbonyl Compounds
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A mesoionic-nitrosotetrazolium-catalyzed aerobic oxidation of alcohols is reported. In the presence of catalytic amounts of 5-nitroso-1,3-diphenyltetrazolium tetrafluoroborate (5 mol-%) and nitric acid (20 mol-%), a wide range of alcohols are oxidized to the corresponding aldehydes and ketones in yields of 53–100 % at room temperature under ambient air or oxygen conditions. This oxidation shows a strong preference for secondary alcohols over primary alcohols; sterically hindered alcohols are also smoothly oxidized. A mechanism involving a nitroso/NOx catalytic cycle is proposed.
- Matsukawa, Yuta,Hirashita, Tsunehisa,Araki, Shuki
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p. 1359 - 1363
(2018/04/02)
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- An alkoxyamine compound, alkoxy alcohol oxidation catalyst and method of using the alcohol oxidation
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PROBLEM TO BE SOLVED: To provide a novel alkoxyamine compound which can be easily manufactured and applied suitably as an alcohol oxidation catalyst capable of exerting sufficiently high catalytic activity in oxidation of primary and secondary alcohols.SOLUTION: There is provided an alkoxyamine compound with a homoadamantane skeleton represented by the general formula (1) in the figure. [In the formula (1), Rand Rare each independently any one selected from the group consisting of a hydrogen atom and alkyl groups that may be substituted.
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Paragraph 0096; 0099-0100
(2017/02/02)
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- Highly efficient aerobic oxidation of alcohols by using less-hindered nitroxyl-radical/copper catalysis: Optimum catalyst combinations and their substrate scope
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The oxidation of alcohols into their corresponding carbonyl compounds is one of the most fundamental transformations in organic chemistry. In our recent report, 2-azaadamantane N-oxyl (AZADO)/copper catalysis promoted the highly chemoselective aerobic oxidation of unprotected amino alcohols into amino carbonyl compounds. Herein, we investigated the extension of the promising AZADO/copper-catalyzed aerobic oxidation of alcohols to other types of alcohol. During close optimization of the reaction conditions by using various alcohols, we found that the optimum combination of nitroxyl radical, copper salt, and solution concentration was dependent on the type of substrate. Various alcohols, including highly hindered and heteroatom-rich ones, were efficiently oxidized into their corresponding carbonyl compounds under mild conditions with lower amounts of the catalysts.
- Sasano, Yusuke,Kogure, Naoki,Nishiyama, Tomohiro,Nagasawa, Shota,Iwabuchi, Yoshiharu
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p. 1004 - 1009
(2015/03/31)
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- Mechanistic insight into aerobic alcohol oxidation using NOx-nitroxide catalysis based on catalyst structure-activity relationships
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The mechanism of an NOx-assisted, nitroxide(nitroxyl radical)-catalyzed aerobic oxidation of alcohols was investigated using a set of sterically and electronically modified nitroxides (i.e., TEMPO, AZADO (1), 5-F-AZADO (2), 5,7-DiF-AZADO (3), 5-MeO-AZADO (4), 5,7-DiMeO-AZADO (5), oxa-AZADO (6), TsN-AZADO (7), and DiAZADO (8)). The motivation for the present study stemmed from our previous observation that the introduction of an F atom at a remote position from the nitroxyl radical moiety on the azaadamantane nucleus effectively enhanced the catalytic activity under typical NOx-mediated aerobic-oxidation conditions. The kinetic profiles of the azaadamantane-N-oxyl-[AZADO (1)-, 5-F-AZADO (2)-, and 5,7-DiF-AZADO (3)]-catalyzed aerobic oxidations were closely investigated, revealing that AZADO (1) showed a high initial reaction rate compared to 5-F-AZADO (2) and 5,7-DiF-AZADO (3); however, AZADO-catalyzed oxidation exhibited a marked slowdown, resulting in ~90% conversion, whereas 5-F-AZADO-catalyzed oxidation smoothly reached completion without a marked slowdown. The reasons for the marked slowdown and the role of the fluoro group are discussed. Oxa-AZADO (6), TsN-AZADO (7), and DiAZADO (8) were designed and synthesized to confirm their comparable catalytic efficiency to that of 5-F-AZADO (2), providing supporting evidence for the electronic effect on the catalytic efficiency of the heteroatoms under NOx-assisted aerobic-oxidation conditions.
- Shibuya, Masatoshi,Nagasawa, Shota,Osada, Yuji,Iwabuchi, Yoshiharu
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p. 10256 - 10268
(2015/02/19)
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- Copper(I)/ABNO-catalyzed aerobic alcohol oxidation: Alleviating steric and electronic constraints of Cu/TEMPO catalyst systems
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Cu/TEMPO catalyst systems promote efficient aerobic oxidation of sterically unhindered primary alcohols and electronically activated substrates, but they show reduced reactivity with aliphatic and secondary alcohols. Here, we report a catalyst system, consisting of (MeObpy)CuI(OTf) and ABNO (MeObpy =4,4′-dimethoxy-2,2′-bipyridine; ABNO = 9-azabicyclo[3.3.1]nonane N-oxyl), that mediates aerobic oxidation of all classes of alcohols, including primary and secondary allylic, benzylic, and aliphatic alcohols with nearly equal efficiency. The catalyst exhibits broad functional group compatibility, and most reactions are complete within 1 h at room temperature using ambient air as the source of oxidant.
- Steves, Janelle E.,Stahl, Shannon S.
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supporting information
p. 15742 - 15745
(2013/11/06)
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- Efficient aerobic oxidation of secondary alcohols at ambient temperature with an ABNO/NOx catalyst system
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New highly practical methods are presented for aerobic oxidation of secondary alcohols with a nitroxyl radical in combination with HNO3, NaNO2, or both as cocatalysts. Diverse nitroxyls are compared, including several novel bicyclic derivatives. Catalyst systems with the readily available nitroxyls, 9-azabicyclo[3.3.1]nonane-N-oxyl (ABNO) and 9-azabicyclo[3.3.1]nonan-3-one-N-oxyl (keto-ABNO), are optimized in acetic acid or acetonitrile as the solvent. The reactions are compatible with substrates bearing diverse functional groups and proceed efficiently under mild conditions at ambient pressure and temperature.
- Lauber, Markus B.,Stahl, Shannon S.
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p. 2612 - 2616
(2013/11/19)
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- C-H modification of 2-azaadamantane: Synthesis of C5-functionalized AZADOs for advanced use
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Regioselective C-H functionalization of N-protected 2-azaadamantane was achieved via a radical-induced bromination. The obtained 5-bromo-2-azaadamantane is readily transformed to arylated/alkylated 2-azaadamantane N-oxyls [AZADOs], which exhibit high catalytic activities for alcohol oxidation. The Japan Institute of Heterocyclic Chemistry.
- Sasano, Yusuke,Nishiyama, Tomohiro,Tomizawa, Masaki,Shibuya, Masatoshi,Iwabuchi, Yoshiharu
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p. 2109 - 2118
(2013/10/22)
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- 3-methyl-4-oxa-5-azahomoadamantane: Alkoxyamine-type organocatalyst for alcohol oxidation
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Strong, silent type: A novel alkoxyamine-type organocatalyst has been discovered for alcohol oxidation (see scheme). The alkoxyamine exhibits a high catalytic activity for the oxidation of alcohols to afford the corresponding carbonyl compounds in high yield by oxidative transformation into an oxoammonium ion, which is proposed to serve as an active species. Copyright
- Sasano, Yusuke,Murakami, Keiichi,Nishiyama, Tomohiro,Kwon, Eunsang,Iwabuchi, Yoshiharu
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supporting information
p. 12624 - 12627
(2013/12/04)
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- METHOD FOR OXIDIZING ALCOHOLS
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A method for oxidizing an alcohol, wherein oxidation is performed in the presence of a compound represented by the following formula (I) and a bulk oxidant, which enables efficient oxidation of secondary alcohols as well as primary alcohols, and can attain high reaction efficiency even when air is used as a bulk oxidant.
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Paragraph 0069; 0070
(2013/06/05)
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- ALPHA-HYDROGEN SUBSTITUTED NITROXYLS AND DERIVATIVES THEREOF AS CATALYSTS
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The present invention relates to novel alpha-hydrogen substituted nitroxyl compounds and their corresponding oxidized (oxoammonium cations) and reduced (hydroxylamine) forms, and to the use of such compounds, inter alia, for (1) oxidation of primary and secondary alcohols to aldehydes and ketones, respectively; (2) resolution of racemic alcohols; (3) desymmetrization of meso-alcohol; (4) as radicals and spin trapping reagents; and (5) as polymerization agents. The present invention further relates to processes for preparing the novel nitroxyl/oxoammonium/ hydroxylamine compounds from the corresponding amines, and to certain novel amine derivatives and their uses. The compounds of the invention as well as the amine precursors are also useful as ligands for transition metals and as organocatalysts in e.g., aldol reactions.
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Page/Page column 37
(2013/08/28)
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- Practical preparation methods for highly active azaadamantane-nitroxyl- radical-type oxidation catalysts
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We have recently disclosed that a less hindered class of nitroxyl radicals, i.e., 2-azaadamantan-N-oxyl (AZADO), 1-Me-AZADO, and 9-azabicyclo[3.3.1]nonan- N-oxyl (ABNO), exhibit marked catalytic activity for the oxidation of alcohols with the aid of environmentally friendly oxidants, offering a green and sustainable option for current alcohol oxidation. Encouraged by their outstanding catalytic performance, we envisioned the development of scalable routes to these radicals that could be extended to the commercialization of these radicals for benchtop use as well as for industrial use as optional reagents that complement TEMPO, the flagship compound of stable nitroxyl radicals. We herein describe short and reproducible preparation methods for AZADO and 1-Me-AZADO, featuring an efficient construction of the 2-azaadamantane skeleton. 1 Introduction 2 1-Me-AZADO and AZADO: First-Generation Syntheses 3 Second-Generation Synthesis of 1-Me-AZADO 4 Synthetic Venture towards 2-Azaadamantane: Second-Generation Synthesis of AZADO 5 Conclusion. Georg Thieme Verlag Stuttgart.
- Shibuya, Masatoshi,Sasano, Yusuke,Tomizawa, Masaki,Hamada, Toshimasa,Kozawa, Masami,Nagahama, Noriaki,Iwabuchi, Yoshiharu
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scheme or table
p. 3418 - 3425
(2012/01/03)
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- 9-azanoradamantane N-Oxyl (Nor-AZADO): A highly active organocatalyst for alcohol oxidation
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A highly active organocatalyst for alcohol oxidation has been developed. 9-Azanoradamantane N-oxyl (Nor-AZADO 4), constituting an unhindered, stable nitroxyl radical, exhibits superior catalytic activity to 2,2,6,6- tetramethylpiperidine-1-oxyl (TEMPO) and AZADOs in the oxidation of alcohols to their corresponding carbonyl compounds.
- Hayashi, Masaki,Sasano, Yusuke,Nagasawa, Shota,Shibuya, Masatoshi,Iwabuchi, Yoshiharu
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experimental part
p. 1570 - 1573
(2012/01/05)
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- An expeditious entry to 9-azabicyclo[3.3.1]nonane N-oxyl (ABNO): Another highly active organocatalyst for oxidation of alcohols
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(Chemical Equation Presented) A practical, three-step synthetic route to 9-azabicyclo[3.3.1] nonane N-oxyl (ABNO, 3), an unhindered, stable class of nitroxyl radical, has been developed. ABNO exhibits a highly active nature compared with TEMPO in the catalytic oxidation of alcohols to their corresponding carbonyl compounds.
- Shibuya, Masatoshi,Tomizawa, Masaki,Sasano, Yusuke,Iwabuchi, Yoshiharu
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supporting information; experimental part
p. 4619 - 4622
(2009/09/08)
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- ALCOHOL OXIDATION CATALYST AND ITS PREPARATION PROCESS
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An alcohol oxidation catalyst which is an organic oxidation catalyst to oxidize an alcohol, which contains azabicyclo [3.3.1]nonane N-oxyl represented by the following formula (1) having an N-oxyl group incorporated in a bicycle[3.3.1]nonane skeleton: wherein X is H2, O or NOH.
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Page/Page column 7-8
(2008/12/08)
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- ALCOHOL OXIDATION CATALYST AND METHOD OF SYNTHESIZING THE SAME
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An organic oxidation catalyst for alcohols which is environmentally less harmful and with which efficient oxidation can be conducted. The oxidation catalyst for alcohols is a 1-alkyl-2-azadamantan-N-oxyl which has a nitroxyl group incorporated in the adamantane skeleton and was synthesized from as a base material a bicyclic compound obtained by the Grob-type ring-opening reaction of 1,3-adamantanediol. Due to the nitroxyl group on the adamantane skeleton, the ±-position hydrogen is stabilized based on Bredt's rule and the stability of the oxoammonium group generated by the oxidation thereof is ensured. Compared to TEMPO, which is a conventional oxidation catalyst, this catalyst is reduced in steric hindrance and is usable in a wide range of reaction fields. Because of this, not only a primary alcohol but a secondary alcohol having a sterically complicated structure, which has been difficult to oxidize with TEMPO, can be oxidized at a high efficiency.
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Page/Page column 12-14
(2008/06/13)
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- 2-Azaadamantane N-oxyl (AZADO) and 1-Me-AZADO: Highly efficient organocatalysts for oxidation of alcohols
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Development of a stable nitroxyl radical class of catalysts, 2-azaadamantane N-oxyl (AZADO) and 1-Me-AZADO, for highly efficient oxidation of alcohols is described. AZADO and 1-Me-AZADO exhibit superior catalytic proficiency to TEMPO, converting various sterically hindered alcohols to the corresponding carbonyl compounds in excellent yields. Copyright
- Shibuya, Masatoshi,Tomizawa, Masaki,Suzuki, Iwao,Iwabuchi, Yoshiharu
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p. 8412 - 8413
(2007/10/03)
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- Recyclable palladium catalyst for highly selective α alkylation of ketones with alcohols
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(Chemical Equation Presented) An air-stable, heterogeneous, and recyclable catalyst composed of palladium nanoparticles entrapped in aluminum hydroxide was applied to a highly selective α alkylation. A wide range of aliphatic and aromatic ketones and primary alcohols were coupled to prepare enones in an O2 atmosphere and ketones in an argon atmosphere (see scheme).
- Kwon, Min Serk,Kim, Namdu,Seo, Seong Hyeok,Park, In Soo,Cheedrala, Ravi Kumar,Park, Jaiwook
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p. 6913 - 6915
(2007/10/03)
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- Reaction of unstabilized iodonium ylides with organoboranes
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Exposure of monocarbonyl iodonium ylides, generated by the ester exchange of (Z)-(2-acetoxyvinyl)-λ3-iodanes with EtOLi, to organoboranes results in a 1,2-shift of a carbon ligand from boron to the ylide carbons, which probably generates hitherto uncharacterized α-boryl ketones.
- Ochiai, Masahito,Tuchimoto, Yoshimi,Higashiura, Nobuyuki
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p. 1505 - 1508
(2007/10/03)
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- Vinylic Organoboranes. 7. Stereoselective Synthesis of (E)-(1-Substituted-1-alkenyl)boronic Esters by the Nucleophilic Substitution of (Z)-(1-Bromo-1-alkenyl)boronic Esters with Organolithium or Grignard Reagents. Isolation and Oxidation to Ketones.
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The title compounds, (E)-R1CH=CR2B(OR)2 (4a-g), are prepared in a highly regio- and stereoselective manner by the reaction of (Z)-R1CH=CBrB(OR)2 (3a-g) with R2Li or R2MgX.The stereochemistry was established in two cases by isolating the E isomers 4 (R1, R2 = n-Bu; R1 = i-Pr, R2 = Me) in pure form and comparing the products with the corresponding Z isomers prepared by hydroboration of appropriate internal alkynes.Oxidation of 4 provides the corresponding ketones, R1CH2COR2, in high yields, confirming the carbon structures of the intermediate.As established previously, protonolysis of these (E)-boronic esters provides a synthesis of the pure (E)-alkenes.
- Brown, Herbert C.,Imai, Toshiro,Bhat, N. G.
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p. 5277 - 5282
(2007/10/02)
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- HIGHLY CHEMOSELECTIVE SYNTHESIS OF KETONES FROM CARBOXYLIC ACIDS AND GRIGNARD REAGENTS USING α-CHLOROENAMINES AS A CONDENSATION REAGENT
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α-Chloroenamines are found to be an effective condensation reagent of carboxylic acids and Grignard reagents under mild conditions to afford chemoselectively the corresponding ketones in high yields and in one-pot operation.
- Fujisawa, Tamotsu,Mori, Toshiki,Higuchi, Kazunobu,Sato, Toshio
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p. 1791 - 1794
(2007/10/02)
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- SIMPLE AND CHEMOSELECTIVE SYNTHESIS OF KETONES FROM CARBOXYLIC ACIDS AND GRIGNARD REAGENTS USING DICHLOROTRIPHENYLPHOSPHORANE
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Dichlorotriphenylphosphorane was found to be a good condensation reagent for synthesis of ketones from carboxylic acids and Grignard reagents under mild conditions.Synthetic utility of the present method is demonstrated by the chemoselective reaction of carboxylic acids possessing such a functional group as halogen, cyano, or carbonyl.
- Fujisawa, Tamotsu,Iida, Sachio,Uehara, Hiroshi,Sato, Toshio
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p. 1267 - 1270
(2007/10/02)
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- Acyclic Stereoselection. 17. Simple Diastereoselection in the Addition of Medium- and Long-Chain n-Alkyl Ketone Lithium Enolates to Aldehydes
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The n-alkyl tert-butyl ketones 1b-d have been prepared and the stereochemistry of their aldol reaction with benzaldehyde has been investigated.As with ketone 1a, ketones 1b-d give Z-enolates that react with benzaldehyde in THF at -78 deg C to give syn aldols.When the aldol additions are carried out in pentane, the syn aldols are also the kinetic products, but syn-anti equilibration is much more rapid in this solvent; after reaction at 25 deg C for 20 min, ketones 1c and 1d give only the anti aldols 3c and 3d.Aldolate syn-anti equilibration becomes more facile as the size of the α-alkyl group increases.Ketone 14 has been prepared and employed in a synthesis of methyl (+/-)-isocorynomycolate; the crucial aldol addition, leading to β-hydroxyketones 15 and 16, proceeds with kinetic stereoselection of only 4.5:1.
- Heathcock, , Clayton H.,Lampe, John
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p. 4330 - 4337
(2007/10/02)
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- ONE-POT SYNTHESIS OF KETONES FROM CARBOXYLIC ACIDS AND GRIGNARD REAGENTS USING N,N-DIPHENYL-p-METHOXYPHENYLCHLOROMETHYLENIMINIUM CHLORIDE
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N,N-Diphenyl-p-methoxyphenylchloromethyleniminium chloride is found to be an effective condensation reagent of carboxylic acids and Grignard reagents under mild conditions to afford the corresponding ketones in high yields.
- Fujisawa, Tamotsu,Mori, Toshiki,Sato, Toshio
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p. 5059 - 5062
(2007/10/02)
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