Heterogeneous Prolinamide-Catalyzed Atom-Economical Synthesis of ?-Thioketones from Bio-Based Enones.

ABSTRACT: Sulfur-containing compounds are a class of important motifs extensively applied in pharmaceutical and pesticidal industries as well as in electrochemistry, toxicant separation, and organic syntheses. Herein, we describe a novel and efficient metal-free catalytic strategy for the rapid synthesis of ?-thioketones from sustainable enone derivatives and thiols via thia-Michael addition enabled by heterogeneous prolinamide. At room temperature, up to 98% yield of ?-thioketones could be obtained over the solid UiO-66-NH-proline catalyst facilely prepared by the covalent immobilization of proline onto UiO-66-NH2 (a well-known metal-organic framework) via a stable amido linkage. A cooperative effect of proline (amino group) and UiO-66-NH2 (in situ-derived amide species) was observed to play a promotional role in the proceeding of thia-Michael addition, resulting in a high TOF value of 1124.3 h-1. A three-component "iminium" intermediate was illustrated to the key species approaching the product ?-thioketone. Moreover, the UiO-66-NH-proline could be easily recovered from the reaction mixture and recycled for at least five times with a slight loss of activity.

SUBMITTER: Zhou X 

PROVIDER: S-EPMC6545542 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature