38379-83-8Relevant academic research and scientific papers
Lewis Base Catalyzed, Sulfenium Ion Initiated Enantioselective, Spiroketalization Cascade
Denmark, Scott E.,Hilby, Kimberly M.
, p. 14250 - 14289 (2021/11/12)
A Lewis base catalyzed, enantioselective sulfenocyclization of alkenes to afford [6,6]spiroketals has been developed. The method uses a chiral Lewis base catalyst with an electrophilic sulfur source to generate enantioenriched thiiranium ion with alkenes. Upon formation, the thiiranium ion is subsequently captured in a cascade-type reaction, wherein a ketone oxygen serves as the nucleophile to open the thiiranium ion and an alcohol provides the secondary cyclization to form biorelevant spiroketals. A variety of electron-rich and electron-neutral E-substituted styrenes form the desired spiroketals in good yields with excellent enantio- and diastereoselectivities. Alkyl-substituted and terminal alkenes participate in the cascade reaction, but with a limited scope compared to the styrenyl substrates. This method allows for rapid formation of highly substituted spiroketals in good yield and excellent enantioselectivity.
Reagent-Controlled Asymmetric Iodolactonization Using Cinchona Alkaloids as Chiral Sources
Wang, Mang,Gao, Lian Xun,Yue, Wei,Mai, Wen Peng
, p. 1023 - 1032 (2007/10/03)
A novel method for reagent-controlled asymmetric iodolactonization of 5-aryl-4-pentenoic acids is reported. This work uses carboxylate ion pairs combined with cinchona alkaloids as chiral sources of carboxylate anion for the first time leading to a mixture of two regio-isomeric iodolactones with moderate enantioselectivity (exo-18.5% ee, endo-35.0% ee) under mild reaction conditions.
