3422-01-3Relevant academic research and scientific papers
Using hydrogen bonding to control carbamate C-N rotamer equilibria
Moraczewski, Alexei L.,Banaszynski, Laura A.,From, Aaron M.,White, Courtney E.,Smith, Bradley D.
, p. 7258 - 7262 (1998)
In chloroform solution, the syn/anti rotamer ratios for AT-(2-pyridyl)carbamates, 3, and JV-phenylcarbamates, 4, are close to 0.05. Addition of the double hydrogen bonding acetic acid moderately stabilizes the syn rotamer of 4, but has no measurable effec
Radical Hydrodehalogenation of Aryl Halides with H2 Catalyzed by a Phenanthroline-Based PNNP Cobalt(I) Complex
Iizuka, Kosuke,Ishizaka, Yusuke,Jheng, Nai-Yuan,Minami, Yasunori,Naganawa, Yuki,Nakajima, Yumiko,Sekiguchi, Akira
, p. 2320 - 2329 (2022/02/16)
Radical hydrodehalogenation of aryl halides (Ar-X; X = Cl, Br, I) is achieved in the presence of atmospheric pressure H2 as a H-atom donor using a Co(I) catalyst bearing a phenanthroline-based PNNP ligand (2,9-bis((diphenylphosphanyl)methyl)-1,10-phenanthroline). The reaction proceeds under mild conditions (1 atm H2) and is applicable to aryl bromides and aryl chlorides with various functional groups. A mechanistic study revealed that the PNNP-Co complex underwent facile H-H cleavage and facilitated a H-atom transfer. This process is mediated by a long-range metal-ligand cooperation of the PNNP-Co system, which includes the dearomatization/aromatization sequence of the phenanthroline ligand backbone. A radical clock experiment demonstrated the Ar-X bond cleavage via a radical mechanism. Further kinetic study supported that the rate-determining step includes electron transfer from the Co center to the substrate, affording a radical pair ArX?- and an odd-electron metal-halide complex [Co(II) + ArX?-]? as a transition state.
Thiamine hydrochloride as a recyclable organocatalyst for the efficient and chemoselective N-tert-butyloxycarbonylation of amines
Ingale, Ajit P.,Garad, Dnyaneshwar N.,Ukale, Dattatraya,Thorat, Nitin M.,Shinde, Sandeep V.
supporting information, p. 3791 - 3804 (2021/11/04)
Thiamin hydrochloride promoted highly efficient and ecofriendly approach has been described for the chemoselective N-tert-butyloxycarbonylation of amines under solvent-free conditions at ambient temperature. The demonstrated approach has been applicable for the N-Boc protection of variety of aliphatic, aryl, heteroaryl amines. The chemoselective protection of amino group occurs in chiral amines and amino alcohol without racemization in high yield. Thiamin hydrochloride is stable, economical, easy to handle and environmentally friendly.
Ultrasound promoted environmentally benign, highly efficient, and chemoselective N-tert-butyloxycarbonylation of amines by reusable sulfated polyborate
Pise, Ashok S.,Ingale, Ajit P.,Dalvi, Navnath R.
supporting information, p. 3768 - 3780 (2021/10/26)
The sulfated polyborate catalyzed an efficient and chemoselective N-tert-butyloxycarbonylation of amines under ultrasonic irradiation is developed. A broad substrate scope has been demonstrated for N-Boc protection of various primary/secondary amines. It allows converting several aliphatic/aryl/heteroaryl amines, amino alcohol, aminoester, and chiral amines to their N-Boc-protected derivatives under solvent-free conditions with excellent yields. The protocol has several advantages such as easy catalyst, and product isolation, short reaction time, excellent yields, outstanding chemoselectivity, and catalyst recyclability, among others. This makes the process practicable, economical, and environmentally benign.
Sulfated tungstate: A highly efficient, recyclable and ecofriendly catalyst for chemoselective N-tert butyloxycarbonylation of amines under the solvent-free conditions
Ingale, Ajit P.,Shinde, Sandeep V.,Thorat, Nitin M.
supporting information, p. 2528 - 2543 (2021/07/02)
Sulfated tungstate catalyzed an efficient and ecofriendly protocol has been described for the chemoselective N-tert-butyloxycarbonylation of amines under the solvent-free conditions at room temperature. The variety of functionalized aliphatic, aromatic and heteroaromatic amines efficiently undergoes the N-tert-butyloxycarbonylation under the developed protocol. The aminoalcohol, aminophenol, aminoester as well as various chiral amines underwent the chemoselective N-Boc protection under the optimized reaction condition. The rapid reaction rate, mild conditions, very good functional group tolerance, excellent yield, solvent-free, easy recovery products and excellent catalyst recyclability are the advantages of this protocol. This makes the protocol feasible, economical and environmentally benign.
Nanoceria as an efficient and green catalyst for the chemoselective N-tert-butyloxycarbonylation of amines under the solvent-free conditions
Garad, Dnyaneshwar N.,Ingale, Ajit P.,Shinde, Sandeep V.,Ukale, Dattatraya
supporting information, p. 1656 - 1668 (2021/04/05)
Nanocerium oxide mediated an efficient and green protocol has been described for the chemoselective N-tert-butyloxycarbonylation of amines under the solvent-free conditions at ambient temperature. Various aliphatic, aromatic and heteroaromatic amines were protected using developed protocol and several functional groups such as alcohol, phenol and ester were well tolerated under these conditions. The rapid reaction rate, mild conditions, very good functional group tolerance, excellent yield, solvent-free, easy recovery products and excellent catalyst recyclability are the advantages of this protocol. This makes the protocol feasible, economical and environmentally benign.
Solvent-freeN-Boc deprotection byex situgeneration of hydrogen chloride gas
De Borggraeve, Wim M.,Gilles, Philippe,Van Mileghem, Seger,Verschueren, Rik H.
supporting information, p. 5782 - 5787 (2021/07/12)
An efficient, scalable and sustainable method for the quantitative deprotection of thetert-butyl carbamate (N-Boc) protecting group is described, using down to near-stoichiometric amounts of hydrogen chloride gas in solvent-free conditions. We demonstrate theex situgeneration of hydrogen chloride gas from sodium chloride and sulfuric acid in a two-chamber reactor, introducing a straightforward method for controlled and stoichiometric release of HCl gas. The solvent-free conditions allow deprotection of a wide variety ofN-Boc derivatives to obtain the hydrochloride salts in quantitative yields. The procedure obviates the need for any work-up or purification steps providing an uncomplicated green alternative to standard methods. Due to the solvent-free, anhydrous conditions, this method shows high tolerance towards acid sensitive functional groups and furnishes expanded functional group orthogonality.
Remarkably Efficient Iridium Catalysts for Directed C(sp2)-H and C(sp3)-H Borylation of Diverse Classes of Substrates
Chattopadhyay, Buddhadeb,Hassan, Mirja Md Mahamudul,Hoque, Md Emdadul
supporting information, p. 5022 - 5037 (2021/05/04)
Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and ortho-selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp3)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp2)-H and C(sp3)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.
In-Cell Generation of Anticancer Phenanthridine Through Bioorthogonal Cyclization in Antitumor Prodrug Development
Maslah, Hichem,Skarbek, Charles,Gourson, Catherine,Plamont, Marie-Aude,Pethe, Stéphanie,Jullien, Ludovic,Le Saux, Thomas,Labruère, Rapha?l
supporting information, p. 24043 - 24047 (2021/10/07)
Pharmacological inactivation of antitumor drugs toward healthy cells is a critical factor in prodrug development. Typically, pharmaceutical chemists graft temporary moieties to existing antitumor drugs to reduce their pharmacological activity. Here, we re
Identification and Profiling of a Novel Diazaspiro[3.4]octane Chemical Series Active against Multiple Stages of the Human Malaria Parasite Plasmodium falciparum and Optimization Efforts
Le Manach, Claire,Dam, Jean,Woodland, John G.,Kaur, Gurminder,Khonde, Lutete P.,Brunschwig, Christel,Njoroge, Mathew,Wicht, Kathryn J.,Horatscheck, André,Paquet, Tanya,Boyle, Grant A.,Gibhard, Liezl,Taylor, Dale,Lawrence, Nina,Yeo, Tomas,Mok, Sachel,Eastman, Richard T.,Dorjsuren, Dorjbal,Talley, Daniel C.,Guo, Hui,Simeonov, Anton,Reader, Janette,Van Der Watt, Mari?tte,Erlank, Erica,Venter, Nelius,Zawada, Jacek W.,Aswat, Ayesha,Nardini, Luisa,Coetzer, Theresa L.,Lauterbach, Sonja B.,Bezuidenhout, Belinda C.,Theron, Anjo,Mancama, Dalu,Koekemoer, Lizette L.,Birkholtz, Lyn-Marie,Wittlin, Sergio,Delves, Michael,Ottilie, Sabine,Winzeler, Elizabeth A.,Smith, Dennis,Fidock, David A.,Street, Leslie J.,Basarab, Gregory S.,Duffy, James,Chibale, Kelly
supporting information, p. 2291 - 2309 (2021/03/01)
A novel diazaspiro[3.4]octane series was identified from a Plasmodium falciparum whole-cell high-throughput screening campaign. Hits displayed activity against multiple stages of the parasite lifecycle, which together with a novel sp3-rich scaffold provided an attractive starting point for a hit-to-lead medicinal chemistry optimization and biological profiling program. Structure-activity-relationship studies led to the identification of compounds that showed low nanomolar asexual blood-stage activity (50 nM) together with strong gametocyte sterilizing properties that translated to transmission-blocking activity in the standard membrane feeding assay. Mechanistic studies through resistance selection with one of the analogues followed by whole-genome sequencing implicated the P. falciparum cyclic amine resistance locus in the mode of resistance.
