Ion-paired Ligands for Palladium-catalyzed Allylic Alkylation under Base-free Conditions

Ohmatsu, Kohsuke; Matsuyama, Naho; Nagato, Yuya; Ooi, Takashi

doi:10.1246/cl.200264

Cited by 1 publication

(1 citation statement)

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“…Alternatively, a catalyst discovery for a variety of organic transformations has been achieved through supramolecular regulation strategies, 3 e.g., by using cationic species 4 or other external molecules functioning as regulation agents, 5 which are placed in the second coordination sphere. 6 An alternative way to influence the activity of catalysts based on positively charged metal centers consists of the structural variation of the counterion. Even though important progress has been made during the past few years in gold(I) chemistry, 7 this strategy remains underexplored in terms of other metals or chemical transformations.…”

Section: ■ Introductionmentioning

confidence: 99%

Counterion Variation: A Useful Lever for Maximizing the Regioselectivity in the Hydroboration of Terminal Alkynes

et al. 2023

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The role of the counterion in metal-catalyzed reactions can be crucial as this often-unconsidered component of the catalyst can modify the performance of the catalyst and influence the reaction rate and/or selectivity of the transformation under study. Herein, we disclose the effects of counterion variation in cationic halogen bond-assembled Rh(I) catalysts in the hydroboration reaction of terminal alkynes, which leads to rather elusive branched (or internal) hydroboration products. Our studies showed that the higher the coordination ability of the counterion, the higher the activity and selectivity toward the hydroboration products. This observation was demonstrated by catalytic and spectroscopic (NMR, IR and X-ray) studies. An array of structurally diverse alkynes was efficiently transformed into the corresponding hydroboration products employing the highest performing catalyst XBphos-Rh-OTf. The practicality of our synthetic method was demonstrated by developing one-pot hydroboration/Csp2-Csp2 coupling processes.

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Section: ■ Introductionmentioning

confidence: 99%