53913-96-5Relevant articles and documents
Synthesis of 4-deoxy-4-nitrosialic acid
Hemeon, Ivan,Bennet, Andrew J.
, p. 2986 - 2992 (2006)
The synthesis of 4-deoxy-4-nitrosialic acid (3,4,5-trideoxy-4-nitro-d- glycero-β-d-galacto-non-2-ulopyranosonic acid, 5), was completed in seven steps starting from d-arabinose. Coupling of the 6-carbon fragment, 2-acetamido-1,2-dideoxy-1-nitro-d-mannitol (6) with ethyl α-(bromomethyl) acrylate afforded a 2: 1 mixture of ethyl 5-acetamido-2,3,4,5-tetradeoxy-2- methylene-4-nitro-d-glycero-d-galacto-nononate (9a-S) and ethyl 5-acetamido-2,3,4,5-tetradeoxy-2-methylene-4-nitro-d-glycero-d-talo-nononate (9a-R). This mixture of enones was subjected to ozonolysis, and following reduction of the ozonide, the resultant products cyclised to the pyranosides. The target compound, ethyl 4-deoxy-4-nitrosialate (11a) was isolated by fractional crystallisation. Hydrolysis of the ethyl ester proved problematic; thus, the synthesis was modified by using tert-butyl α-(bromomethyl) acrylate. Following ozonolysis of the corresponding tert-butyl enoate esters and diastereomer separation, the tert-butyl ester of 4-nitrosialic acid (11b) could be deprotected under acidic conditions to afford 5. The target compound is a useful intermediate for synthesis of a variety of C-4 substituted sialic acid derivatives, and it is synthesised by a modular route. The Royal Society of Chemistry 2006.
Copper-catalyzed radical oxyallylation of olefins for the construction of alkene-containing isoxazolines
He, Xiaoxue,Qian, Lijie,Dai, Yuyu,Yan, Xinhuan,Li, Xiaoqing,Xu, Xiangsheng
supporting information, (2021/05/31)
A radical-mediated approach to alkene oxyallylation using allylic oximes is described. The reaction proceeds under copper-catalytic redox-neutral conditions and tolerates various functional groups. This protocol thus enables the synthesis of structurally valuable isoxazolines and the introduction of a versatile olefin motif in a single step.
Copper-Catalyzed Intermolecular Alkynylation and Allylation of Unactivated C(sp3)-H Bonds via Hydrogen Atom Transfer
Liang, Lei,Guo, Ge,Li, Chen,Wang, Song-Lin,Wang, Yue-Hui,Guo, Hai-Ming,Niu, Hong-Ying
supporting information, p. 8575 - 8579 (2021/11/13)
We describe Cu-catalyzed intermolecular alkynylation and allylation of unactivated C(sp3)-H bonds with singly occupied molecular orbital-philes (SOMO-philes) via hydrogen atom transfer (HAT). Employing N-fluoro-sulfonamide as a HAT reagent, a set of subst
Photoredox-Coupled F-Nucleophilic Addition: Allylation of gem-Difluoroalkenes
Liu, Haidong,Ge, Liang,Wang, Ding-Xing,Chen, Nan,Feng, Chao
supporting information, p. 3918 - 3922 (2019/02/19)
A novel strategy for the expedient construction of CF3-embeded tertiary/quarternary carbon centers was developed by taking advantage of photoredox catalysis. Thanks to a key step of single-electron oxidation, electron-rich gem-difluoroalkenes, which otherwise are essentially reluctant towards F-nucleoplilic addition, now readily participate in this fluoroallylation reaction. Furthermore, this strategy provides an elegant example for the generation, as well as functionalization, of α-CF3-substituted benzylic radical intermediates using cheap and readily available starting materials.
Photoredox-Catalyzed Cyclopropanation of 1,1-Disubstituted Alkenes via Radical-Polar Crossover Process
Luo, Wenping,Yang, Yi,Fang, Yewen,Zhang, Xinxin,Jin, Xiaoping,Zhao, Guicai,Zhang, Li,Li, Yan,Zhou, Wanli,Xia, Tingting,Chen, Bin
supporting information, p. 4215 - 4221 (2019/08/16)
The photoredox-neutral catalyzed cyclopropanation of 1,1-disubstituted alkenes via radical addition-anionic cyclization cascade has been successfully developed. Another new protocol based on photocatalytic allylation and cyclopropanation cascade was also described between allylic halide and halomethyl radical. In addition to the successful use of bis-catecholato silicates as the alkyl radical precursors, the acyl and alkyl radicals derived from 1,4-dihydropyridines were also engaged in this radical-polar crossover process. The competing experiments displayed that the 3-exo-tet mode of cyclization preferred over 4-exo and 5-exo cyclization modes, allowing for the selective 3-exo-tet cyclization. The superior nucleofuge character of bromide over chloride and tosylate has been demonstrated in the reaction of bromomethyl radical with homoallylic (pseudo)halides. This new protocol is characterized by its redox-neutral process, broad substrate scope, mild conditions, and good functional-group compatibility. (Figure presented.).
Catalytic Asymmetric Synthesis of Quaternary Barbituric Acids
Del Pozo, Sandra,Vera, Silvia,Oiarbide, Mikel,Palomo, Claudio
supporting information, p. 15308 - 15311 (2017/11/06)
The catalytic asymmetric α-functionalization of prochiral barbituric acids, a subtype of pseudosymmetric 1,3-diamides, to yield the corresponding 5,5-disubstituted (quaternary) derivatives remains essentially unsolved. In this study 2-alkylthio-4,6-dioxopirimidines are designed as key 1,3-diamide surrogates that perform exceedingly in amine-squaramide catalyzed C-C bond forming reactions with vinyl ketones or Morita-Baylis-Hillmann-type allyl bromides as electrophiles. Mild acid hydrolysis of adducts affords barbituric acid derivatives with an in-ring quaternary carbon in unprecedented enantioselectivity, offering valuable materials for biological evaluations.
Palladium-Catalyzed Direct Intramolecular C-N Bond Formation: Access to Multisubstituted Dihydropyrroles
Jiang, Bing,Meng, Fei-Fan,Liang, Qiu-Ju,Xu, Yun-He,Loh, Teck-Peng
, p. 914 - 917 (2017/02/26)
A palladium-catalyzed intramolecular amination of alkenes with retention of olefin functionalization was achieved under mild reaction conditions. In the presence of palladium catalyst, the tosyl-protected amine can directly couple with a double bond to provide versatile dihydropyrrole derivatives in moderate to excellent yields.
Enantioselective synthesis of xanthatin
Bergmann, Andreas,Reiser, Oliver
supporting information, p. 7613 - 7615 (2014/07/07)
The enantioselective synthesis of cytostatic and antibiotic xanthatin (1 a) is reported. As a key intermediate, a bicyclic compound 2 was identified, which can be readily synthesized from methyl-2-furoic acid in diastereo- and enantiomerically pure form.
The chemical development and scale-up of sampatrilat
Dunn, Peter J.,Hughes, Michael L.,Searle, Patricia M.,Wood, Albert S.
, p. 244 - 253 (2013/09/06)
The discovery and scale-up of two routes to sampatrilat are described. The first Chemical R and D route used a side product from another development project to accelerate drug supply and expedite the early development programme. The second, more efficient Chemical R and D route had the potential for commercialisation and used an environmentally friendly variant of the Baylis-Hillman reaction, and an asymmetric Michael addition as key steps. Full preparative details for the aminomethacrylate 4, a potentially useful chiral synthon, are given for the first time, along with full experimental details of the asymmetric Michael addition to make the chiral glutarate 5. Finally, a striking polymorph case history is described.
Versatile synthesis of inhibitors of late enzymes in the bacterial pathway to lysine
Steger, Matthias,Young, Douglas W.
, p. 7935 - 7956 (2007/10/03)
Modification of our 'ring switching' reaction has allowed us to develop a versatile synthesis of potential inhibitors of the late enzymes in the bacterial pathway to lysine. The methodology is applicable to solid phase combinatorial synthesis.
