31915-94-3Relevant academic research and scientific papers
THE INFLUENCE OF (ORGANO)METALLICS "METAL-TUNING" ON STEREO- AND REGIO-CHEMICAL CONVERGENCE IN REACTIONS OF ALLYLIC CARBANIONS WITH ALDEHYDES
Yamamoto, Yoshinori,Saito, Yoshizaku,Maruyama, Kazuhiro
, p. 311 - 318 (1985)
Although the reaction of heterosubstituted allylic carbanions (2) with aldehydes generally produces a mixture of the γ- and α-adducts (4 and 3), syn-3 and anti-3 can be prepared either exclusively or predominantly by the proper choice of the organometallic compound added.
Cobalt-catalyzed regioselective stereoconvergent Markovnikov 1,2-hydrosilylation of conjugated dienes
Sang, Hui Leng,Yu, Songjie,Ge, Shaozhong
, p. 973 - 978 (2018)
We report the first stereoconvergent Markovnikov 1,2-hydrosilylation of conjugated dienes using catalysts generated from bench-stable Co(acac)2 and phosphine ligands. A wide range of E/Z-dienes underwent this Markovnikov 1,2-hydrosilylation in a stereoconvergent manner, affording (E)-allylsilanes in high isolated yields with high stereoselectivities (E/Z = >99;:;1) and high regioselectivities (b/l up to > 99;:;1). Mechanistic studies revealed that this stereoconvergence stems from a σ-π-σ isomerization of an allylcobalt species generated by the 1,4-hydrometalation of Z-dienes. In addition, a cobalt catalyst that can only catalyze the hydrosilylation of the E-isomer of an (E/Z)-diene was identified, which allows the separation of the (Z)-isomer from an isomeric mixture of (E/Z)-dienes. Furthermore, asymmetric hydrosilylation of (E)-1-aryl-1,3-dienes was studied with Co(acac)2/(R)-difluorphos and good enantioselectivities (er up to 90;:;10) were obtained.
Palladium-Catalyzed Asymmetric Tandem Denitrogenative Heck/Tsuji-Trost of Benzotriazoles with 1,3-Dienes
Li, Yin-Lin,Wu, Hai-Hong,Zhang, Junliang,Zhang, Pei-Chao
supporting information, p. 13010 - 13015 (2021/09/07)
The asymmetric denitrogenative cycloaddition has emerged as a powerful tool to build chiral aza-heterocyles. However, only one example of asymmetric denitrogenative cycloaddition of benzotriazole with unsaturated hydrocarbons has been explored so far, bec
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.
Enantioselective Addition of Pyrazoles to Dienes**
Dong, Vy M.,Jiu, Alexander Y.,Slocumb, Hannah S.,Yang, Xiao-Hui,Yeung, Charles S.
supporting information, p. 19660 - 19664 (2021/08/06)
We report the first enantioselective addition of pyrazoles to 1,3-dienes. Secondary and tertiary allylic pyrazoles can be generated with excellent regioselectivity. Mechanistic studies support a pathway distinct from previous hydroaminations: a Pd0-catalyzed ligand-to-ligand hydrogen transfer (LLHT). This hydroamination tolerates a range of functional groups and advances the field of diene hydrofunctionalization.
Photoinduced Palladium-Catalyzed Carbofunctionalization of Conjugated Dienes Proceeding via Radical-Polar Crossover Scenario: 1,2-Aminoalkylation and beyond
Gevorgyan, Vladimir,Kurandina, Daria,Shing Cheung, Kelvin Pak,Yata, Tetsuji
supporting information, p. 9932 - 9937 (2020/06/27)
A photoinduced palladium-catalyzed 1,2-carbofunctionalization of conjugated dienes has been developed. This mild modular approach, which does not require employment of exogeneous photosensitizers and external oxidants, allows for efficient and highly regio- and stereoselective synthesis of a broad range of allylic amines from readily available 1,3-dienes, alkyl iodides, and amines. Employment of O- and C-nucleophiles toward oxyalkylation and dialkylation products was also demonstrated. A putative π-allyl palladium radical-polar crossover path is proposed as a key event in this three-component coupling process. The utility of this protocol is highlighted by its application for derivatization of several amine-containing drugs.
Cu-Catalyzed highly regioselective 1,2-hydrocarboxylation of 1,3-dienes with CO2
Zhang, Penglin,Zhou, Zhanglang,Zhang, Rumeng,Zhao, Qian,Zhang, Chun
supporting information, p. 11469 - 11472 (2020/10/12)
A practical copper-catalyzed highly regioselective 1,2-hydrocarboxylation of terminal 1,3-diene with carbon dioxide has been developed. Under mild reaction conditions, this chemistry afforded 2-benzyl-β,γ-unsaturated acid derivatives as products, which are a kind of important unit for bio-active molecules and versatile precursors for organic synthesis, with good functional group tolerance. The key intermediate in this transformation is illustrated by control experiments.
Enantioselective Coupling of Dienes and Phosphine Oxides
Nie, Shao-Zhen,Davison, Ryan T.,Dong, Vy M.
supporting information, p. 16450 - 16454 (2018/12/11)
We report a Pd-catalyzed intermolecular hydrophosphinylation of 1,3-dienes to afford chiral allylic phosphine oxides. Commodity dienes and air stable phosphine oxides couple to generate organophosphorus building blocks with high enantio- and regiocontrol. This method constitutes the first asymmetric hydrophosphinylation of dienes.
Ni-Catalyzed Site-Selective Dicarboxylation of 1,3-Dienes with CO2
Tortajada, Andreu,Ninokata, Ryo,Martin, Ruben
supporting information, p. 2050 - 2053 (2018/02/19)
A site-selective catalytic incorporation of multiple CO2 molecules into 1,3-dienes en route to adipic acids is described. This protocol is characterized by its mild conditions, excellent chemo- and regioselectivity and ease of execution under CO2 (1 atm), including the use of bulk butadiene and/or isoprene feedstocks.
Photo-induced Decarboxylative Heck-Type Coupling of Unactivated Aliphatic Acids and Terminal Alkenes in the Absence of Sacrificial Hydrogen Acceptors
Cao, Hui,Jiang, Heming,Feng, Hongyu,Kwan, Jeric Mun Chung,Liu, Xiaogang,Wu, Jie
supporting information, p. 16360 - 16367 (2018/11/27)
1,2-Disubstituted alkenes such as vinyl arenes, vinyl silanes, and vinyl boronates are among the most versatile building blocks that can be found in every sector of chemical science. We herein report a noble-metal-free method of accessing such olefins through a photo-induced decarboxylative Heck-type coupling using alkyl carboxylic acids, one of the most ubiquitous building blocks, as the feedstocks. This transformation was achieved in the absence of external oxidants through the synergistic combination of an organo photo-redox catalyst and a cobaloxime catalyst, with H2 and CO2 as the only byproducts. Both control experiments and DFT calculations supported a radical-based mechanism, which eventually led to the development of a selective three-component coupling of aliphatic carboxylic acids, acrylates, and vinyl arenes. More than 90 olefins across a wide range of functionalities were effectively synthesized with this simple protocol.
