Oxone-mediated oxidative carbon-heteroatom bond cleavage: synthesis of benzoxazinones from benzoxazoles with α-oxocarboxylic acids
作者:Hua Wang、Hua Yang、Yiping Li、Xin-Hua Duan
DOI:10.1039/c3ra47660j
日期:——
A metal-free oxidative cleavage of benzoxazoles using Oxone as an oxidant has been developed. The in situ formed o-aminophenol has been proved to react successfully with α-oxocarboxylic acids affording the benzoxazinones in moderate to good yields.
the synthesis of quinazolinones, quinoxalinones, benzooxazinones, and benzothiazoles from the reactions of α-keto acids with 2-aminobenzamides, benzene-1,2-diamines, 2-aminophenols, and 2-aminobenzenethiols, respectively, is described. The reactions were conducted under catalyst-free conditions, using water as the sole solvent with no additive required, and successfully applied to the synthesis of sildenafil
Unexpected TFA-catalyzed tandem reaction of benzo[d]oxazoles with 2-oxo-2-arylacetic acids: synthesis of 3-aryl-2H-benzo[b][1,4]oxazin-2-ones and cephalandole A
TFA-catalyzed reaction of benzo[d]oxazoles with 2-oxo-2-arylacetic acids: synthesis of 3-aryl-2H-benzo[b][1,4]oxazin-2-ones and the natural product cephalandole A.
The development of biomimetic chemistry based on the NAD(P)H with hydrogen gas as terminal reductant is a long‐standing challenge. Through rational design of the chiral and regenerable NAD(P)H analogues based on planar‐chiral ferrocene, a biomimetic asymmetric reduction has been realized using bench‐stable Lewis acids as transfer catalysts. A broad set of alkenes and imines could be reduced with up
alkenes with up to 99% yield and 99% enantiomeric excess (ee). The mechanism of chiral regenerable NAD(P)Hmodels was investigated as well. Isotope-labeling reactions indicated that chiral NAD(P)Hmodels were regenerated by the ruthenium complex under hydrogen gas first, and then the hydride of NAD(P)Hmodels was transferred to unsaturated bonds in the presence of transfer catalysts. In addition, density