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 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-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.).
