Heterocyclic communications | |
Heterocyclic synthesis via catalysis of N-heterocyclic carbenes: very classical and very modern chemical species | |
article | |
Takashi Okano1  | |
[1] Laboratory of Chemistry, The Jikei University School of Medicine | |
关键词: azolium ylide; benzoin condensation; Breslow intermediate; enantioselective reaction; N-heterocyclic carbene; Stetter reaction; | |
DOI : 10.1515/hc-2013-0075 | |
学科分类:内科医学 | |
来源: De Gruyter | |
【 摘 要 】
After a long history of medical and biochemical investigations of vitamin B 1 , N -heterocyclic carbenes (NHCs) have recently been used as organocatalysts for a variety of synthetic reactions. This review article highlights the application of NHC-catalyzed reactions including enantioselective reactions to the heterocyclic synthesis. NHC-catalyzed benzoin condensation and Stetter reaction of ether- and amine-linked aldehydes give four- to six-membered oxygen and nitrogen heterocycles. NHC-catalyzed conjugate additions of enals to ketones and imines afford γ-lactones and γ-lactams. When the NHC-catalyzed reaction intermediates of enals are protonated, the reaction of the resulting enols with enones and ene-imines furnish formal hetero-Diels-Alder products. Acyl fluoride and esters can be activated by NHCs, and subsequent aldol and Michael reactions give β-lactones. Oxidation of intermediates derived from enals or the intermediates from ynals provide unsaturated acyl azolium which are transformed into cyclic products via subsequent nucleophilic reactions. NHCs also catalyze [2+2] cycloadditions of ketenes and other heterocumulenes and ring expansion of cyclic aldehydes.
【 授权许可】
CC BY|CC BY-NC-ND
【 预 览 】
Files | Size | Format | View |
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RO202107200002547ZK.pdf | 3176KB | download |