Nickel-catalyzed olefination of cyclic benzylic dithioacetals by Grignard reagents. Scope and mechanism
摘要:
The details of the first nickel-catalyzed olefination of cyclic dithioacetals to form substituted styrenes and aryl-substituted 1,4-pentadienes are described. The reaction represents a new synthetic use of the dithioacetal functionality. Only nickel complexes catalyzed these cross-coupling reactions; palladium complexes displayed no catalytic activity under the reaction conditions employed. Selective coupling occurred. A mechanism for the reaction is proposed. The experimental evidence indicates that, in these nickel-catalyzed couplings, cyclic dithioacetals are more reactive than their acyclic analogues. This increased reactivity appears to be the result of maintaining the two sulfur atoms in close proximity to each other by the use of a short chain of methylene groups.
Study of DABCO Based Acidic Ionic Liquids Strategy for the Synthesis of 1,3-Dithiolane and Benzothiazolo-[2,3-b]-quinazolin-1-one Derivatives
作者:Priyanka Pinate、Abdulfatah Abdullah Abdu Saifan、Sangita Makone
DOI:10.1007/s10562-023-04411-1
日期:2024.4
explains the synthesis of 1,3-dithiolane and benzothiazolo-[2,3-b]-quinazolin-1-one derivatives employing DABCO-based ionic liquids as a facile, sustainable, and recyclablecatalyst. FT-IR, NMR, and mass spectrometry were used to characterize synthetic compounds. The current approach displays a number of advantages, including an affordable and environmentally friendly catalyst, green solvent media
Phosphorus pentoxide supported on silica gel (P2O5/SiO2) efficiently acts as a highly active and reusable catalyst for cyclic and non-cyclic S,S-acetalization of a variety of carbonyl compounds under mild, solvent-free and ambient conditions. This method offers significant advantages such as high conversion, clean work-up, short reaction times and simplicity in operation.[GRAPHICS].