102245-02-3Relevant academic research and scientific papers
Concise synthesis and applications of enantiopure spirobiphenoxasilin-diol and its related chiral ligands
Liu, Tao,Wang, Biqin,Wang, Peng,Wu, Yichen,Xu, Wen-Qiang,Yang, Lei
, p. 13365 - 13368 (2021/12/17)
The development of chiral architectures for chiral ligand and catalyst discovery is essential for asymmetric catalysis. Herein, we report the concise synthesis of a Si-centered spirocyclic skeleton, spirobiphenoxasilin-diol (SPOSiOL), and its derived chiral ligands. Using the chemical resolution method, the optical SPOSiOL could be obtained in high yield on a gram scale. Preliminary studies indicated that this ligand scaffold has great potential in transition metal-catalyzed asymmetric reactions. This finding further highlights that the Si-centered spirocyclic scaffolds are of great value in asymmetric catalysis. This journal is
Silver-Promoted Direct Phosphorylation of Bulky C(sp2)-H Bond to Build Fully Substituted β-Phosphonodehydroamino Acids
Cao, Hao-Qiang,Liu, Hao-Nan,Liu, Zhe-Yuan,Qiao, Baokun,Zhang, Fa-Guang,Ma, Jun-An
supporting information, p. 6414 - 6419 (2020/09/02)
A general and practical cross-dehydrogenative coupling protocol between readily available trisubstituted α,β-dehydro α-amino carboxylic esters and H-phosphites is described. This C(sp2)-H phosphorylation reaction proceeds with absolute Z-selectivity promoted by silver salt in a radical relay manner. The bulky tetrasubstituted β-phosphonodehydroamino acids were obtained in grams and added new modules to the toolkit for peptide modifications.
Ni(ii)-Catalyzed vinylic C-H functionalization of 2-acetamido-3-arylacrylates to access isotetronic acids
Das, Eshani,Mal, Dipakranjan,Roy, Avijit,Roy, Biswajit
supporting information, p. 3697 - 3706 (2020/06/03)
A ligand-free Ni(ii)-catalyzed cascade annulation reaction for the synthesis of 4-aryl-substituted isotetronic acids from 2-acetamido-3-arylacrylatesviavinylic C-H functionalization is reported. The reaction proceeds through heteroatom guided electrophilic insertion of nickel to the vinylic double bond followed by annulation with dibromomethane. This unconventional route features cascade steps, sole product formation, multiple functional group tolerance, low cost of catalysts and reagents, and readily available starting materials. Using this method, various aryl-substituted isotetronic acids have been synthesized which are biologically relevant. The annulation of 2-acetamido-3-arylacrylates has also been assessed with 1,2-dichloroethane, which resulted in the rearranged annulated products of 5-methyl substituted isotetronic acids.
Hypervalent iodane mediated reactions of: N -acetyl enamines for the synthesis of oxazoles and imidazoles
Xu, Kang,Yang, Ruiqi,Yang, Shuang,Jiang, Cheng,Ding, Zhenhua
supporting information, p. 8977 - 8981 (2019/10/28)
A hypervalent iodane reagent used for the intramolecular cyclization of N-acetyl enamines and intermolecular cyclocondensation of enamines and nitriles was investigated. The reaction was performed under mild conditions and gave oxazoles and imidazoles, respectively, in moderate to excellent yields. This transformation exhibits good reactivity, selectivity and functional group tolerance. The selectivity of the intra- or intermolecular reaction is dependent on the structure of N-acetyl enamines.
Systematic methodology for the development of biocatalytic hydrogen-borrowing cascades: Application to the synthesis of chiral α-substituted carboxylic acids from α-substituted α,β-unsaturated aldehydes
Knaus, Tanja,Mutti, Francesco G.,Humphreys, Luke D.,Turner, Nicholas J.,Scrutton, Nigel S.
supporting information, p. 223 - 233 (2015/02/19)
Ene-reductases (ERs) are flavin dependent enzymes that catalyze the asymmetric reduction of activated carbon-carbon double bonds. In particular, α,β-unsaturated carbonyl compounds (e.g. enals and enones) as well as nitroalkenes are rapidly reduced. Conversely, α,β-unsaturated esters are poorly accepted substrates whereas free carboxylic acids are not converted at all. The only exceptions are α,β-unsaturated diacids, diesters as well as esters bearing an electron-withdrawing group in α- or β-position. Here, we present an alternative approach that has a general applicability for directly obtaining diverse chiral α-substituted carboxylic acids. This approach combines two enzyme classes, namely ERs and aldehyde dehydrogenases (Ald-DHs), in a concurrent reductive-oxidative biocatalytic cascade. This strategy has several advantages as the starting material is an α-substituted α,β-unsaturated aldehyde, a class of compounds extremely reactive for the reduction of the alkene moiety. Furthermore no external hydride source from a sacrificial substrate (e.g. glucose, formate) is required since the hydride for the first reductive step is liberated in the second oxidative step. Such a process is defined as a hydrogen-borrowing cascade. This methodology has wide applicability as it was successfully applied to the synthesis of chiral substituted hydrocinnamic acids, aliphatic acids, heterocycles and even acetylated amino acids with elevated yield, chemo- and stereo-selectivity. A systematic methodology for optimizing the hydrogen-borrowing two-enzyme synthesis of α-chiral substituted carboxylic acids was developed. This systematic methodology has general applicability for the development of diverse hydrogen-borrowing processes that possess the highest atom efficiency and the lowest environmental impact. This journal is
Temperature-controlled bidirectional enantioselectivity in a dynamic catalyst for asymmetric hydrogenation
Storch, Golo,Trapp, Oliver
supporting information, p. 3580 - 3586 (2015/03/18)
Asymmetric catalysis using enantiomerically pure catalysts is one of the most widely used methods for the preparation of enantiomerically pure compounds. The separate synthesis of both enantiomerically pure compounds requires tedious and time-consuming pr
Synthesis of oxazoles from enamides via phenyliodine diacetate-mediated intramolecular oxidative cyclization
Zheng, Yunhui,Li, Xuming,Ren, Chengfeng,Zhang-Negrerie, Daisy,Du, Yunfei,Zhao, Kang
, p. 10353 - 10361 (2013/01/15)
A group of functionalized oxazoles were synthesized in moderate to good yields from enamides via phenyliodine diacetate (PIDA)-mediated intramolecular cyclization. The main advantageous features of the present method include its broad substrate scope and the heavy-metal-free characteristic of the oxidative carbon-oxygen bond formation process.
Ligand-free palladium catalysed Heck reaction of methyl 2-acetamido acrylate and aryl bromides as key step in the synthesis of enantiopure substituted phenylalanines
Willans, Charlotte E.,Mulders, Jan M.C.A.,de Vries, Johannes G.,de Vries, André H.M.
, p. 494 - 497 (2007/10/03)
A range of substituted aryl bromides were coupled with methyl 2-acetamido acrylate using ligand-free palladium catalysis. Subsequently asymmetric hydrogenation with Rh/MonoPhos yielded substituted phenylalanines in high enantioselectivities (e.e. 92-99%).
Photo-stimulated heterolysis of the C(=O)-O bond in (Z)-N-acetyl-α-dehydrophenylalanine aryl ester derivatives
Hoshina, Hideki,Nakayama, Kentaro,Igarashi, Tetsutaro,Sakurai, Tadamitsu
, p. 1239 - 1245 (2007/10/03)
The irradiation of the title compounds [(Z)-1] in acetonitrile was found to give (Z)-2-methyl-4-(4-chlorobenzylidene)-5(4H)-oxazolone [(Z)-2] and phenols or naphthols (3), along with minor amounts of the Fries-rearranged products (4) and (E)-2. Solvent and substituent effects on the product distribution confirmed that the heterolytic cleavage of the ester C(=O)-O bond of the starting 1 in the excited singlet state is responsible for appearance of both 2 and 3 whereas 4 is derived from the homolysis (of the ester bond) taking place in competition with the predominant heterolysis of this bond. It was suggested that there is a pronounced contribution of charge transfer from the aryloxy oxygen to the parent π system in the excited singlet state.
Formation of isoquinoline derivatives by the irradiation of N-acetyl-α-dehydrophenylalanine ethyl ester and its derivatives
Hoshina, Hideki,Tsuru, Hitoshi,Kubo, Kanji,Igarashi, Tetsutaro,Sakurai, Tadamitsu
, p. 2261 - 2274 (2007/10/03)
The irradiation of a nitrogen-purged acetonitrile solution of the title compounds (1) with Pyrex filtered light was found to give isoquinoline derivatives (2) via the excited state (Z)-isomers, whereas in methanol 1-azetine derivative was also detected al
