5159-41-1Relevant academic research and scientific papers
MACROCYCLIC COMPOUNDS USEFUL AS CHITINASE INHIBITORS
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Paragraph 0128; 0165-0166, (2021/07/29)
The present invention relates to macrocyclic compounds of formula (I) and their use as chitinase inhibitors as well as to pharmaceutical compositions and methods of preparation thereof. The compounds can in particular be used in the treatment, prevention and/or amelioration of asthma.
Pd(II)-Catalyzed Synthesis of Benzocyclobutenes by β-Methylene-Selective C(sp3)-H Arylation with a Transient Directing Group
Chen, Xiangyang,Hoskin, John F.,Houk, K. N.,Provencher, Philip A.,Sorensen, Erik J.,Wong, Jonathan J.,Yu, Jin-Quan
supporting information, p. 20035 - 20041 (2021/12/09)
Methylene-selective C-H functionalization is a significant hurdle that remains to be addressed in the field of Pd(II) catalysis. We report a Pd(II)-catalyzed synthesis of benzocyclobutenes by methylene-selective C(sp3)-H arylation of ketones. The reaction utilizes glycine as a transient directing group and a 2-pyridone ligand, which may govern the methylene selectivity by making intimate molecular associations with the substrate during concerted metalation-deprotonation. This reaction is shown to be highly selective for intramolecular methylene C(sp3)-H arylation, thus enabling sequential C(sp3)-H functionalization.
A General Method for Photocatalytic Decarboxylative Hydroxylation of Carboxylic Acids
Khan, Shah Nawaz,Zaman, Muhammad Kashif,Li, Ruining,Sun, Zhankui
, p. 5019 - 5026 (2020/05/01)
A general and practical method for decarboxylative hydroxylation of carboxylic acids was developed through visible light-induced photocatalysis using molecular oxygen as the green oxidant. The addition of NaBH4 to in situ reduce the unstable peroxyl radical intermediate much broadened the substrate scope. Different sp3 carbon-bearing carboxylic acids were successfully employed as substrates, including phenylacetic acid-type substrates, as well as aliphatic carboxylic acids. This transformation worked smoothly on primary, secondary, and tertiary carboxylic acids.
One-Pot Synthesis and Conformational Analysis of Six-Membered Cyclic Iodonium Salts
Caspers, Lucien D.,Spils, Julian,Damrath, Mattis,Lork, Enno,Nachtsheim, Boris J.
, p. 9161 - 9178 (2020/08/14)
Two one-pot procedures for the construction of carbon-bridged diaryliodonium triflates and tetrafluoroborates are described. Strong Br?nsted acids enable the effective Friedel-Crafts alkylation with diversely substituted o-iodobenzyl alcohol derivatives, providing diphenylmethane scaffolds, which are subsequently oxidized and cyclized to the corresponding dibenzo[b,e]iodininium salts. Based on NMR investigations and density functional theory (DFT) calculations, we could verify the so-far-undescribed existence of two stable isomers in cyclic iodonium salts substituted with aliphatic side chains in the carbon bridge.
Iodolopyrazolium Salts: Synthesis, Derivatizations, and Applications
Boelke, Andreas,Caspers, Lucien D.,Kuczmera, Thomas J.,Lork, Enno,Nachtsheim, Boris J.
supporting information, p. 7261 - 7266 (2020/10/05)
The synthesis of iodolopyrazolium triflates via an oxidative cyclization of 3-(2-iodophenyl)-1H-pyrazoles is described. The reaction is characterized by a broad substrate scope, and various applications of these novel cyclic iodolium salts acting as useful synthetic intermediates are demonstrated, in particular in site-selective ring openings. This was finally applied to generate derivatives of the anti-inflammatory drug celecoxib. Their application as highly active halogen-bond donors is shown as well.
Nickel-Catalyzed Asymmetric Reductive 1,2-Carboamination of Unactivated Alkenes
He, Jun,Xue, Yuhang,Han, Bo,Zhang, Chunzhu,Wang, You,Zhu, Shaolin
supporting information, p. 2328 - 2332 (2020/01/08)
Starting from diverse alkene-tethered aryl iodides and O-benzoyl-hydroxylamines, the enantioselective reductive cross-electrophilic 1,2-carboamination of unactivated alkenes was achieved using a chiral pyrox/nickel complex as the catalyst. This mild, modular, and practical protocol provides rapid access to a variety of β-chiral amines with an enantioenriched aryl-substituted quaternary carbon center in good yields and with excellent enantioselectivities. This process reveals a complementary regioselectivity when compared to Pd and Cu catalysis.
KMnO4-catalyzed chemoselective deprotection of acetate and controllable deacetylation-oxidation in one pot
Gurawa, Aakanksha,Kumar, Manoj,Rao, Dodla S.,Kashyap, Sudhir
supporting information, p. 16702 - 16707 (2020/10/27)
A novel and efficient protocol for chemoselective deacetylation under ambient conditions was developed using catalytic KMnO4. The stoichiometric use of KMnO4 highlighted the dual role of a heterogeneous oxidant enabling direct access to aromatic aldehydes in one-pot sequential deacetylation-oxidation. The reaction employed an alternative solvent system and allowed the clean transformation of benzyl acetate to sensitive aldehyde in a single step while preventing over-oxidation to acids. Use of inexpensive and readily accessible KMnO4 as an environmentally benign reagent and the ease of the reaction operation were particularly attractive, and enabled the controlled oxidation and facile cleavage of acetate in a preceding step. This journal is
Storing redox equivalent in the phenalenyl backbone towards catalytic multi-electron reduction
Bhunia, Mrinal,Sahoo, Sumeet Ranjan,Shaw, Bikash Kumar,Vaidya, Shefali,Pariyar, Anand,Vijaykumar, Gonela,Adhikari, Debashis,Mandal, Swadhin K.
, p. 7433 - 7441 (2019/08/15)
Storing and transferring electrons for multi-electron reduction processes are considered to be the key steps in various important chemical and biological transformations. In this work, we accomplished multi-electron reduction of a carboxylic acid via a hydrosilylation pathway where a redox-active phenalenyl backbone in Co(PLY-O,O)2(THF)2, stores electrons and plays a preponderant role in the entire process. This reduction proceeds by single electron transfer (SET) from the mono-reduced ligand backbone leading to the cleavage of the Si-H bond. Several important intermediates along the catalytic reduction reaction have been isolated and well characterized to prove that the redox equivalent is stored in the form of a C-H bond in the PLY backbone via a ligand dearomatization process. The ligand's extensive participation in storing a hydride equivalent has been conclusively elucidated via a deuterium labelling experiment. This is a rare example where the ligand orchestrates the multielectron reduction process leaving only the metal to maintain the conformational requirements and fine tunes the electronics of the catalyst.
Regioselectivity Influences in Platinum-Catalyzed Intramolecular Alkyne O-H and N-H Additions
Costello, Jeff P.,Ferreira, Eric M.
supporting information, p. 9934 - 9939 (2019/12/24)
The steric and electronic drivers of regioselectivity in platinum-catalyzed intramolecular hydroalkoxylation are elucidated. A branch point is found that divides the process between 5-exo and 6-endo selective processes, and enol ethers can be accessed in good yields for both oxygen heterocycles. The main influence arises from an electronic effect, where the alkyne substituent induces a polarization of the alkyne that leads to preferential heteroatom attack at the more electron-deficient carbon. The electronic effects are studied in other contexts, including hydroacyloxylation and hydroamination, and similar trends in directionality are predominant although not uniformly observed.
Selective Hydroboration of Carboxylic Acids with a Homogeneous Manganese Catalyst
Barman, Milan K.,Das, Kuhali,Maji, Biplab
, p. 1570 - 1579 (2019/01/30)
Catalytic reduction of carboxylic acid to the corresponding alcohol is a challenging task of great importance for the production of a variety of value-added chemicals. Herein, a manganese-catalyzed chemoselective hydroboration of carboxylic acids has been developed with a high turnover number (>99?000) and turnover frequency (>2000 h-1) at 25 °C. This method displayed tolerance of electronically and sterically differentiated substrates with high chemoselectivity. Importantly, aliphatic long-chain fatty acids, including biomass-derived compounds, can efficiently be reduced. Mechanistic studies revealed that the reaction occurs through the formation of active manganese-hydride species via an insertion and bond metathesis type mechanism.
