330983-74-9Relevant academic research and scientific papers
Site-Selective Acceptorless Dehydrogenation of Aliphatics Enabled by Organophotoredox/Cobalt Dual Catalysis
Zhou, Min-Jie,Zhang, Lei,Liu, Guixia,Xu, Chen,Huang, Zheng
supporting information, p. 16470 - 16485 (2021/10/20)
The value of catalytic dehydrogenation of aliphatics (CDA) in organic synthesis has remained largely underexplored. Known homogeneous CDA systems often require the use of sacrificial hydrogen acceptors (or oxidants), precious metal catalysts, and harsh reaction conditions, thus limiting most existing methods to dehydrogenation of non- or low-functionalized alkanes. Here we describe a visible-light-driven, dual-catalyst system consisting of inexpensive organophotoredox and base-metal catalysts for room-temperature, acceptorless-CDA (Al-CDA). Initiated by photoexited 2-chloroanthraquinone, the process involves H atom transfer (HAT) of aliphatics to form alkyl radicals, which then react with cobaloxime to produce olefins and H2. This operationally simple method enables direct dehydrogenation of readily available chemical feedstocks to diversely functionalized olefins. For example, we demonstrate, for the first time, the oxidant-free desaturation of thioethers and amides to alkenyl sulfides and enamides, respectively. Moreover, the system's exceptional site selectivity and functional group tolerance are illustrated by late-stage dehydrogenation and synthesis of 14 biologically relevant molecules and pharmaceutical ingredients. Mechanistic studies have revealed a dual HAT process and provided insights into the origin of reactivity and site selectivity.
BF3·OEt2-mediated: Syn -selective Meyer-Schuster rearrangement of phenoxy propargyl alcohols for Z -β-aryl-α,β-unsaturated esters
Puri, Surendra,Hari Babu, Madala,Sridhar Reddy, Maddi
, p. 7001 - 7009 (2016/07/30)
Synthesis of Z-β-aryl-α,β-unsaturated esters from readily available 1-aryl-3-phenoxy propargyl alcohols is achieved via a BF3-mediated syn-selective Meyer-Schuster rearrangement under ambient conditions. The reaction mechanism is postulated to involve an electrophilic borylation of an allene intermediate as the key step to kinetically control the stereoselectivity.
Palladium-catalyzed carbonylation of aryl, alkenyl, and allyl halides with phenyl formate
Ueda, Tsuyoshi,Konishi, Hideyuki,Manabe, Kei
, p. 3100 - 3103 (2012/07/27)
Highly efficient palladium-catalyzed carbonylation of aryl, alkenyl, and allyl halides with phenyl formate is reported. This procedure does not use carbon monoxide and affords one-carbon-elongated carboxylic acid phenyl esters in excellent yields. The reaction proceeds smoothly under mild conditions and tolerates a wide range of functional groups including aldehyde, ether, ketone, ester, and cyano groups. Furthermore, a variety of heteroaromatic bromides can be converted to the corresponding phenyl esters in high yields.
Dinuclear zinc catalyzed asymmetric spirannulation reaction: An umpolung strategy for formation of α-alkylated-α-hydroxyoxindoles
Trost, Barry M.,Hirano, Keiichi
, p. 2446 - 2449 (2012/07/27)
A highly diastereo- and enantioselective formal [3 + 2] cycloaddition of α,β-unsaturated esters and 3-hydroxyoxindoles catalyzed by a dinuclear zinc-ProPhenol complex is reported. The stereoselective Michael additions of 3-hydroxyoxindoles and the subsequent transesterifications afford spirocyclic δ-lactones.
The Synthesis of Phenyl Carboxylates from p-Bromophenol and Carboxylic Acid
Hashimoto, Shizunobu,Furukawa, Isao
, p. 2839 - 2840 (2007/10/02)
The reaction of p-bromophenol with carboxylic acids in the presence of triphenylphosphine and triethylamine proceeded at a high temperature, with the elimination of hydrogen bromide, to give phenyl carboxylates and small amounts of p-bromophenyl carboxylates.
