Microwave-Assisted Synthesis of 3,1-Benzoxazin-2-ones from 3-Hydroxyoxindoles
作者:Oscar R. Suárez-Castillo、Claudia I. Bautista-Hernández、Maricruz Sánchez-Zavala、Myriam Meléndez-Rodríguez、Araceli Sierra-Zenteno、Martha S. Morales-Ríos、Pedro Joseph-Nathan
DOI:10.3987/com-12-12472
日期:——
A general protocol for the synthesis of 3,1-benzoxazin-2-ones 18 from 3-hydroxyoxindoles 16 in a two steps sequence through phenylsuccinates or phenylpropionates 17 is described. Best reaction conditions for ring opening of 16 to succinates or propionates 17 were achieved using alcohol/silica gel, while cyclization of 17 to benzoxazinones 18 was easily done with HCl/alcohol. It was also found that 17 and 18 can be transesterified using HCl/alcohol. Most transformations were carried out by traditional heating and by microwave (MW) irradiation to accelerate reaction rates.
Enantioselective, Intermolecular [<sub>π</sub>2+<sub>σ</sub>2] Photocycloaddition Reactions of 2(1<i>H</i>)-Quinolones and Bicyclo[1.1.0]butanes
作者:Morgane de Robichon、Thilo Kratz、Frederike Beyer、Julian Zuber、Christian Merten、Thorsten Bach
DOI:10.1021/jacs.3c08404
日期:——
enantioselectively to 2(1H)-quinolones upon irradiation (λ = 366 nm) in the presence of a chiral complexing agent. A two-point hydrogenbond between the quinolone and the template is responsible for stereocontrol in the photocycloaddition reaction. The reaction leads to the formation of products with a chiral bicyclo[2.1.1]hexane skeleton in high enantiomeric excess (91–99% ee). The chiraltemplate can be almost