Continuous-Flow Synthesis of Arylthio-Cyclopropyl Carbonyl Compounds

Abstract

The straightforward, continuous-flow synthesis of cyclopropyl carbaldehydes and ketones has been developed starting from 2-hydroxycyclobutanones and aryl thiols. This acid-catalyzed mediated procedure allows access to the multigram and easily scalable synthesis of cyclopropyl adducts under mild conditions, using reusable Amberlyst-35 as a catalyst. The resins, suitably ground and used for filling steel columns, have been characterized via TGA, ATR, SEM and BET analyses to describe the physical–chemical properties of the packed bed and the continuous-flow system in detail. To highlight the synthetic versatility of the arylthiocyclopropyl carbonyl compounds, a series of selective oxidation reactions have been performed to access sulfoxide and sulfone carbaldehyde cyclopropanes, oxiranes and carboxylic acid derivatives.

Continuous flow oxidation of alkynes with KMnO4 for the synthesis of 1,2-diketone derivatives

“…In recent years, we faced the need to synthesize increasing amounts of aliphatic 1,2-diketones as a starting material to carry out our research. 19 Although we have evaluated various synthetic protocols, none of these were found to be comparable to the oxidation of alkynes based on the use of potassium permanganate.…”