Carbonyl Activation by Selenium- and Tellurium-Based Chalcogen Bonding in a Michael Addition Reaction.

ABSTRACT: In the last years the use of chalcogen bonding-the noncovalent interaction involving electrophilic chalcogen centers-in noncovalent organocatalysis has received increased interest, particularly regarding the use of intermolecular Lewis acids. Herein, we present the first use of tellurium-based catalysts for the activation of a carbonyl compound (and only the second such activation by chalcogen bonding in general). As benchmark reaction, the Michael-type addition between trans-crotonophenone and 1-methylindole (and its derivatives) was investigated in the presence of various catalyst candidates. Whereas non-chalcogen-bonding reference compounds were inactive, strong rate accelerations of up to 1000 could be achieved by bidentate triazolium-based chalcogen bond donors, with product yields of >90?% within 2?h of reaction time. Organotellurium derivatives were markedly more active than their selenium and sulphur analogues and non-coordinating counterions like BAr^F ₄ provide the strongest dicationic catalysts.

SUBMITTER: Wonner P 

PROVIDER: S-EPMC7027547 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature