Polystyrene-Supported Acyclic Diaminocarbene Palladium Complexes in Sonogashira Cross-Coupling: Stability vs. Catalytic Activity

Abstract

Two types of immobilized on the amino-functionalized polystyrene-supported acyclic diaminocarbene palladium complexes (ADC-Pd II ) are investigated under Sonogashira cross-coupling conditions. Depending on substituents in the diaminocarbene fragment immobilized ADC-Pd II , systems are found to have different catalytic activity and stability regarding Pd-leaching. Pd II -diaminocarbenes possessing protons at both nitrogen atoms smoothly decompose into Pd 0 -containing species providing a catalytic "cocktail system" with high activity and ability to reuse within nine runs. Polymer-supported palladium (II) complex bearing NBn-C carbene -NH-moiety exhibits greater stability while noticeably lower activity under Sonogashira cross-coupling. Four molecular ADC-Pd II complexes are also synthesized and investigated with the aim of confirming proposed base-promoted pathway of ADC-Pd II conversion through carbodiimide into an active Pd 0 forms.

Exploring Supramolecular Assembly Space of Cationic 1,2,4-Selenodiazoles: Effect of the Substituent at the Carbon Atom and Anions

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