25070-74-0Relevant articles and documents
Oxidations of pyrrolidines and piperidines to afford CH-functionalized isopropyl-1-carboxylate congeners
Gunawan, Steven,Bedard, Nathan,Foley, Christopher,Hulme, Christopher
, (2021)
This article describes the action of iodine(III) reagents [diacetoxyiodobenzene, PhI(OAc)2, and iodosobenzene, (PhIO)n] in conjunction with TMSBr which act as functional bromine equivalents in unique oxidations of saturated, carbamate protected N-heterocycles. Interestingly, during this work, treatment of the same carbamates with molecular bromine alone afforded similar products, which were sequestered by the solvent methanol.
Red-light-mediated BartonMcCombie reaction
Ichii, Naoki,Ogura, Akihiro,Shibata, Kouhei,Takao, Ken-Ichi
supporting information, p. 936 - 941 (2020/11/09)
A red-light-mediated BartonMcCombie reaction is described, in which chlorophyll a is used as a photocatalyst and tris(trimethylsilyl)silane or Hantzsch ester is used as the hydrogen source. The reaction can be performed with a set of easily available equipment and reagents, and a variety of linear and cyclic xanthates could be applied. In contrast to the traditional conditions, the reaction does not involve toxic organotin or an explosive radical initiator. The reaction mechanism was analyzed both by experiments and computation, and it was suggested that the radical chain mechanism initiated by excitation of complex followed by charge transfer is likely to be operative.
Carbamate Synthesis Using a Shelf-Stable and Renewable C1 Reactant
Dobi, Zoltán,Reddy, B. Narendraprasad,Renders, Evelien,Van Raemdonck, Laurent,Mensch, Carl,De Smet, Gilles,Chen, Chen,Bheeter, Charles,Sergeyev, Sergey,Herrebout, Wouter A.,Maes, Bert U. W.
, p. 3103 - 3114 (2019/06/24)
4-Propylcatechol carbonate is a shelf-stable, renewable C1 reactant. It is easily prepared from renewable 4-propylcatechol (derived from wood) and dimethyl carbonate (derived from CO2) using a reactive distillation system. In this work, the 4-propylcatechol carbonate is used for the two-step synthesis of carbamates under mild reaction conditions. In the first step, 4-propylcatechol carbonate is treated with an alcohol at 50–80 °C in the presence of a Lewis acid catalyst, such as Zn(OAc)2?2 H2O. With liquid alcohols, no solvent is used and with solid alcohols 2-methyltetrahydrofuran is used as solvent. In the second step, the alkyl 2-hydroxy-propylphenyl carbonate intermediates obtained react with amines at room temperature in 2-methyltetrahydrofuran, forming the target carbamates and the byproduct 4-propylcatechol, which can be recycled into a carbonate reactant.
A Redox Strategy for Light-Driven, Out-of-Equilibrium Isomerizations and Application to Catalytic C-C Bond Cleavage Reactions
Ota, Eisuke,Wang, Huaiju,Frye, Nils Lennart,Knowles, Robert R.
supporting information, p. 1457 - 1462 (2019/01/25)
We report a general protocol for the light-driven isomerization of cyclic aliphatic alcohols to linear carbonyl compounds. These reactions proceed via proton-coupled electron-transfer activation of alcohol O-H bonds followed by subsequent C-C β-scission of the resulting alkoxy radical intermediates. In many cases, these redox-neutral isomerizations proceed in opposition to a significant energetic gradient, yielding products that are less thermodynamically stable than the starting materials. A mechanism is presented to rationalize this out-of-equilibrium behavior that may serve as a model for the design of other contrathermodynamic transformations driven by excited-state redox events.
C(sp3)?H Cyanation Promoted by Visible-Light Photoredox/Phosphate Hybrid Catalysis
Wakaki, Takayuki,Sakai, Kentaro,Enomoto, Takafumi,Kondo, Mio,Masaoka, Shigeyuki,Oisaki, Kounosuke,Kanai, Motomu
supporting information, p. 8051 - 8055 (2018/06/15)
Inspired by the reaction mechanism of photo-induced DNA cleavage in nature, a C(sp3)?H cyanation reaction promoted by visible-light photoredox/phosphate hybrid catalysis was developed. Phosphate radicals, generated by one-electron photooxidation of phosphate salt, functioned as a hydrogen-atom-transfer catalyst to produce nucleophilic carbon radicals from C(sp3)?H bonds with a high bond-dissociation energy. The resulting carbon radicals were trapped by a cyano radical source (TsCN) to produce the C?H cyanation products. Due to the high functional-group tolerance and versatility of the cyano group, the reaction will be useful for realizing streamlined building block syntheses and late-stage functionalization of drug-like molecules.
Nickel-Catalyzed Barton Decarboxylation and Giese Reactions: A Practical Take on Classic Transforms
Qin, Tian,Malins, Lara R.,Edwards, Jacob T.,Merchant, Rohan R.,Novak, Alexander J. E.,Zhong, Jacob Z.,Mills, Riley B.,Yan, Ming,Yuan, Changxia,Eastgate, Martin D.,Baran, Phil S.
supporting information, p. 260 - 265 (2016/12/30)
Two named reactions of fundamental importance and paramount utility in organic synthesis have been reinvestigated, the Barton decarboxylation and Giese radical conjugate addition. N-hydroxyphthalimide (NHPI) based redox-active esters were found to be conv
N-Urethane protection of amines and amino acids in an ionic liquid
Di Gioia,Gagliardi,Leggio,Leotta,Romio,Liguori
, p. 63407 - 63420 (2015/08/11)
An efficient, solvent-free protocol for the N-fluorenylmethoxycarbonylation and N-benzyloxycarbonylation of amines is described. The reaction of aliphatic and aromatic amines with FmocOSu and Cbz-Osu in [Bmim][BF4] at room temperature afforded the corresponding N-urethane derivatives in excellent yields and do not require any further purification. The method has been extended to the N-Fmoc and N-Cbz protection of amino acids. Absence of bases, very short reaction times, high yields, selectivity and ease of product separation are some advantages of this protocol.
Hydrodecarboxylation of Carboxylic and Malonic Acid Derivatives via Organic Photoredox Catalysis: Substrate Scope and Mechanistic Insight
Griffin, Jeremy D.,Zeller, Mary A.,Nicewicz, David A.
supporting information, p. 11340 - 11348 (2015/09/21)
A direct, catalytic hydrodecarboxylation of primary, secondary, and tertiary carboxylic acids is reported. The catalytic system consists of a Fukuzumi acridinium photooxidant with phenyldisulfide acting as a redox-active cocatalyst. Substoichiometric quantities of Hünigs base are used to reveal the carboxylate. Use of trifluoroethanol as a solvent allowed for significant improvements in substrate compatibilities, as the method reported is not limited to carboxylic acids bearing α heteroatoms or phenyl substitution. This method has been applied to the direct double decarboxylation of malonic acid derivatives, which allows for the convenient use of dimethyl malonate as a methylene synthon. Kinetic analysis of the reaction is presented showing a lack of a kinetic isotope effect when generating deuterothiophenol in situ as a hydrogen atom donor. Further kinetic analysis demonstrated first-order kinetics with respect to the carboxylate, while the reaction is zero-order in acridinium catalyst, consistent with another finding suggesting the reaction is light limiting and carboxylate oxidation is likely turnover limiting. Stern-Volmer analysis was carried out in order to determine the efficiency for the carboxylates to quench the acridinium excited state.
Tandem ring-closing metathesis/transfer hydrogenation: Practical chemoselective hydrogenation of alkenes
Connolly, Timothy,Wang, Zhongyu,Walker, Michael A.,McDonald, Ivar M.,Peese, Kevin M.
, p. 4444 - 4447 (2015/01/09)
An operationally simple chemoselective transfer hydrogenation of alkenes using ruthenium metathesis catalysts is presented. Of great practicality, the transfer hydrogenation reagents can be added directly to a metathesis reaction and effect hydrogenation of the product alkene in a single pot at ambient temperature without the need to seal the vessel to prevent hydrogen gas escape. The reduction is applicable to a range of alkenes and can be performed in the presence of aryl halides and benzyl groups, a notable weakness of Pd-catalyzed hydrogenations. Scope and mechanistic considerations are presented.
Nickel-catalyzed reductive cyclization of alkyl dihalides
Xue, Weichao,Xu, Hailiang,Liang, Zhuye,Qian, Qun,Gong, Hegui
supporting information, p. 4984 - 4987 (2014/12/11)
The reductive coupling protocol to intramolecular cyclization of dihaloalkanes is presented. It leads to five- and six-membered rings, with the former being more efficient. The incorporation of secondary alkyl halides generally promotes coupling efficiency. To the best of our knowledge, this is the first catalytic ring-closure reaction arising from dihaloalkanes under chemical reductive conditions.
