- Synthesis of Benzylic Alcohols by C-H Oxidation
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Selective methylene C-H oxidation for the synthesis of alcohols with a broad scope and functional group tolerance is challenging due to the high proclivity for further oxidation of alcohols to ketones. Here, we report the selective synthesis of benzylic alcohols employing bis(methanesulfonyl) peroxide as an oxidant. We attempt to provide a rationale for the selectivity for monooxygenation, which is distinct from previous work; a proton-coupled electron transfer mechanism (PCET) may account for the difference in reactivity. We envision that our method will be useful for applications in the discovery of drugs and agrochemicals.
- Tanwar, Lalita,B?rgel, Jonas,Ritter, Tobias
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p. 17983 - 17988
(2019/11/14)
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- Highly enantioselective dynamic kinetic resolution of alkyl aryl carbinols carrying a trimethylsilyl group with a highly active lipoprotein lipase preparation
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Abstract The kinetic and dynamic kinetic resolution of alkyl aryl carbinols carrying a trimethylsilyl group with a highly active lipase preparation containing lipoprotein lipase, dextrin, and ionic surfactant 1 has been explored. It was found that all the trimethylsilyl-containing substrates were accepted by lipoprotein lipase-dextrin 1 (LPL-D1) with perfect enantioselectivity (E = >200). As a result, the dynamic kinetic resolution of these substrates with LPL-D1 in the presence of a Ru-based racemization catalyst provided single enantiomeric products (>99% ee) with good yields. Furthermore, the dynamic kinetic resolution products were readily desilylated or halodesilylated to yield enantiopure alkyl aryl carbinols. Thus a useful protocol for the highly enantioselective synthesis of alkyl aryl carbinols, particularly those carrying a long alkyl chain (C6-C10) has been established.
- Cho, Jeonghun,Lee, Jusuk,Park, Jaiwook,Kim, Mahn-Joo
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p. 840 - 845
(2015/08/18)
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- Tandem α-Alkylation/Asymmetric Transfer Hydrogenation of Acetophenones with Primary Alcohols
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Tandem α-alkylation/asymmetric transfer hydrogenation of acetophenones with primary alcohols, mediated by a single ruthenium catalyst, is described. Under optimized reaction conditions and with use of [Ru(p-cymene)Cl2]2 in combination with an amino acid hydroxyamide ligand, the chiral secondary alcohol products were isolated in moderate yields and in moderate to good enantiomeric excess (up to 89 % ee). One catalyst - one pot - two reactions. Acetophenones are initially alkylated with primary alcohols by the borrowing hydrogen methodology. The alkylation products are directly converted to enantiomerically enriched secondary alcohols.
- Kovalenko, Oleksandr O.,Lundberg, Helena,Hübner, Dennis,Adolfsson, Hans
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supporting information
p. 6639 - 6642
(2016/02/19)
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- Syntheses with organoboranes. XIII. Synthesis of ω-(4-bromophenyl)alkanoic acids and their borylation
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ω-(4-Bromophenyl)alkanoic acids 2c-e were obtained from 1-bromo-4-alkenylbenzenes 5c-e by hydroboration-thermal isomerization-oxidation. Their esters 11c-e were transformed in good yields into the corresponding boronates 12c-e by the cross-coupling reaction with (10) in an ionic liquid, [bmim][BF4]. The use of pinacolborane for the coupling reaction in the ionic liquid gave debromination products, and low yields of 12c-e. Ethyl 3-(4-bromophenyl)propanoate (7c) was transformed into ethyl 3-(4-[1,3,2]dioxaborolanyl)propanoate (9c) by the cross-coupling with [2,2′]bi[[1,3,2]dioxaborinanyl].
- Zaidlewicz, Marek,Wolan, Andrzej
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p. 129 - 135
(2007/10/03)
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- Pyran-2-ones and 5,6-dihydropyran-2-ones useful for treating hyperplasia and other diseases
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Certain 2H-pyran-2-ones are useful for treating benign prostatic hypertrophy or hyperplasia, prostatic cancer, alopecia, hirsutism, acne vulgaris and seborrhea.
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- Preparation and Properties of Tertiary p-Alkylarylphosphines containing Straight-chain Alkyl Groups
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A series of tris(p-alkylaryl)phosphines with straight-chain alkyl groups, P(p-C6H4-CnH2n+1)3 where n=2-9, have been prepared by reaction of phosphorus trichloride with the Grignard reagent derived from the corresponding p-bromoalkylbenzene.When n=2 and 3 the phosphines are crystalline solids, but for n>3 they are viscous oils up to n=9, which is a waxy solid.The phosphines have been characterised by microanalysis, and i.r., 1H and 31P n.m.r., and mass spectrometry.The p-substituted-arylphosphines are more sensitive than triphenylphosphine to air; aerial oxidation converts them exclusively into the corresponding phosphine oxides, in contrast to trialkylphosphines which are oxidised to a complex mixture of products.The complexing ability of the new phosphines (PAr3) is demonstrated by their ready displacement of 1,5-cyclo-octadiene (cod) from (M=Pd and Pt) to yield trans- and cis-, respectively.
- Franks, Stephen,Hartley, Frank R.
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p. 2233 - 2237
(2007/10/02)
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