151-10-0Relevant articles and documents
Enantioselective total synthesis of (-)-blennolide A
Tietze, Lutz F.,Ma, Ling,Reiner, Johannes R.,Jackenkroll, Stefan,Heidemann, Sven
, p. 8610 - 8614 (2013)
Blennolide A can be synthesized through an enantioselective domino-Wacker/carbonylation/methoxylation reaction of 7 a with 96 % ee and an enantioselective Wacker oxidation of 7 b with 89 % ee. Further transformations led to the α,β-unsaturated ester (E)-17, which was subjected to a highly selective Michael addition, introducing a methyl group to give 18 a. After a threefold oxidation and an intramolecular acylation, the tetrahydroxanthenone 4 was obtained, which could be transformed into (-)-blennolide A (ent-1) in a few steps. Domino effect: An enantioselective domino-Wacker/carbonylation/methoxylation process and an enantioselective Wacker oxidation are the key steps in the first total synthesis of the fungal metabolite blennolide A (see scheme). Copyright
Carbon Kinetic Isotope Effects and the Mechanisms of Acid-Catalyzed Decarboxylation of 2,4-Dimethoxybenzoic Acid and CO2 Incorporation into 1,3-Dimethoxybenzene
Vandersteen, Adelle A.,Howe, Graeme W.,Sherwood Lollar, Barbara,Kluger, Ronald
, p. 15049 - 15053 (2017)
The rate of decarboxylation of 2,4-dimethoxybenzoic acid (1) is accelerated in parallel to the extent that the carboxyl group acquires a second proton (1H+). However, the conjugate acid would resist C-C bond breaking as that would lead to formation of doubly protonated CO2. An alternative via formation of a higher-energy protonated phenyl tautomer (2H+) prior to C-C bond breaking would produce protonated CO2, an energetically inaccessible species that can be avoided by transfer of the carboxyl proton to water in the same step. Headspace sampling of CO2 that evolves in the acid-catalyzed process and analysis by GC-IRMS gives a smaller than expected value of 1.022 for the carbon kinetic isotope (CKIE), k12/k13. While this value establishes that C-C cleavage is part of the rate-determining process, intrinsic CKIEs for decarboxylation reactions are typically greater than 1.03. Computational analysis of the C-C bond cleavage from 2H+ gives an intrinsic CKIE of 1.051 and suggests two partially rate-determining steps in the decarboxylation of 1: transfer of the second carboxyl proton to the adjacent phenyl carbon and C-C cleavage in which the carboxyl proton is also transferred to water. Applying the principle of microscopic reversibility to fixation of CO2 in acidic solutions reveals the importance of proton transfers to both carbon and oxygen in the overall fixation process.
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Thoms,Siebeling
, p. 2135 (1911)
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Polyfuryl(aryl)alkanes and their derivatives. 12. C-fur bond cleavage in the series of polyfuryl(aryl)alkanes
Butin,Stroganova,Kul'nevich
, p. 153 - 157 (1996)
Reactions taking place with cleavage of the C-Fur bond are examined. It was established that disproportionation in two directions, leading to the formation of tris(5-methyl-2-furyl)methane, takes place when 3,4-dimethoxyphenylbis(5-methyl-2-furyl)methane is boiled in an acidic medium. The acid-catalyzed reaction of 5-methylfurfural with ethylene glycol leads to the formation of either 2-(5-methyl-2-furyl)-1,3-dioxolane or tris(5-methyl-2-furyl)methane, depending on the catalyst. The treatment of 2-(5-methyl-2-furyl)-1,3-dioxolane or gemtris(5·methyl-2-furyl)ethane with trityl perchlorate leads to tris(5-methyl-2-furyl)carbenium or bis(5-methyl-2-furyl)methylcarbenium perchlorates respectively. 1996 Plenum Publishing Corporation.
Zweig et al.
, p. 4124,4125 (1964)
Nickel-Catalyzed Hydrodeoxygenation of Aryl Sulfamates with Alcohols as Mild Reducing Agents
Matsuo, Kasumi,Kuriyama, Masami,Yamamoto, Kosuke,Demizu, Yosuke,Nishida, Koyo,Onomura, Osamu
, p. 4449 - 4460 (2021/08/25)
The nickel-catalyzed hydrodeoxygenation of aryl sulfamates has been developed with alcohols as mild reductants. A variety of functional groups and heterocycles were tolerated in this reaction system to give the desired products in high yields. In addition, the gram-scale process and stepwise cine-substitution were also achieved with high efficiency.
Exploiting a silver-bismuth hybrid material as heterogeneous noble metal catalyst for decarboxylations and decarboxylative deuterations of carboxylic acids under batch and continuous flow conditions
?tv?s, Sándor B.,Fül?p, Ferenc,Kónya, Zoltán,Kukovecz, ákos,Márton, András,Mészáros, Rebeka,Pálinkó, István,Szabados, Márton,Varga, Gábor
, p. 4685 - 4696 (2021/07/12)
Herein, we report novel catalytic methodologies for protodecarboxylations and decarboxylative deuterations of carboxylic acids utilizing a silver-containing hybrid material as a heterogeneous noble metal catalyst. After an initial batch method development, a chemically intensified continuous flow process was established in a simple packed-bed system which enabled gram-scale protodecarboxlyations without detectable structural degradation of the catalyst. The scope and applicability of the batch and flow processes were demonstrated through decarboxylations of a diverse set of aromatic carboxylic acids. Catalytic decarboxylative deuterations were achieved on the basis of the reaction conditions developed for the protodecarboxylations using D2O as a readily available deuterium source.