4‐(Dimethylamino)pyridine‐Catalyzed (3+2) Annulation of Pyrazoledione‐Derived Morita–Baylis–Hillman Carbonates with 2‐Arylideneindane‐1,3‐Diones: An Access to Dispirocyclic Compounds
lyzed (3+2) annulation of pyrazoledione-derived Morita–Baylis–Hillman (MBH) carbonates with 2-arylideneindane-1,3-diones has been developed to afford various multifunctional spiropyrazole derivatives in 16–99% yields with 3:2–>20:1 diastereoselectivities. As a type of Lewis-base receptor, the pyrazoledione-derived MBH carbonates will function as a key substrate in organocatalyzed annulation reactions
Lewis acid-catalyzed enantioselective Friedel-Crafts reaction of pyrazole-4,5-diones with β-naphthol
作者:Yangmian Lu、Jindong Li、Weizhi Gu、Ning Li、Zhenggen Zha、Zhiyong Wang
DOI:10.1016/j.cclet.2021.12.038
日期:2022.8
tetrasubstituted chiral center were prepared by virtue of a Lewis acid-catalyzed Friedel-Crafts reaction, in which a chiralcopper complex was employed as the catalyst. This reaction can be carried out smoothly under mild condition to afford the pyrazolone derivatives with high yields (up to 85%) and excellent enantioselectivities (up to 99%). In addition, the gram scale synthesis proved the practicality
developed, the asymmetric construction of six-membered oxa-spiropyrazolones is still a challenging task in organic synthesis. Herein, we describe the [4 + 2] annulation of cyclobutanones and pyrazoline-4,5-diones for the efficient synthesis of δ-lactone-fused spiropyrazolone derivatives with generally high yields and good enantioselectivities under mild conditions. The successful scale-up synthesis and further
benzoxazine compounds is unveiled utilizing vinyl benzoxazinanones reacted with pyrazolone 4,5-diones, which extends the application of vinyl benzoxazinanones with ketones. This asymmetric catalytic [4+2] cycloaddition reaction demonstrates a broad substrate scope with functional group tolerance in yields of up to 76% and up to 96% ee. A facile scale-up and straightforward conversion to diversely substituted