Abstract
Sequential double hydrofunctionalizationalization of alkynes is a powerful method to construct useful vicinal compounds. Herein, we report a cobalt-catalyzed sequential hydrosilylation/hydrohydrazidation of alkynes to afford 1,2-N,Si compounds via ligand relay catalysis. A phenomenon of ligand relay is found that the tridentate anionic N-ligand (OPAQ) could capture the cobalt ion from bidentate neutral P-ligand (Xantphos) cobalt complex. This protocol uses three abundant chemical feedstocks, alkynes, silanes, and diazo compounds, and also features operationally simple, mild conditions, low catalyst loading (1 mol%), and excellent functional group tolerance. The 1,2-N,Si compounds can be easily further derivatized to afford various substituted silane derivatives via Si-H functionalization, alcohols via Fleming-Tamao oxidation, free amines and amides via N-N bond cleavage and protection. The asymmetric reaction could also be carried out to afford chiral products with up to 86% ee. The ligand relay has been supported by control experiments and absorption spectra.
Highlights
Sequential double hydrofunctionalizationalization of alkynes is a powerful method to construct useful vicinal compounds
To the best of our knowledge, this ligand relay catalysis has not been used in sequential double hydrofunctionalization of alkynes
Our group is quite interested in earth-abundant transitionmetal-catalyzed reactions of alkenes and alkynes[11–15,34–37], here, we report a cobalt-catalyzed chemo- and regioselective sequential hydrosilylation/hydrohydrazidation of terminal alkynes via ligand relay catalysis with hydrosilanes and diazo compounds to afford vicinal amino and silyl products bearing both N-H bond and Si-H bond which could be further derivatized (Fig. 2b)
Summary
Sequential double hydrofunctionalizationalization of alkynes is a powerful method to construct useful vicinal compounds. We report a cobalt-catalyzed sequential hydrosilylation/hydrohydrazidation of alkynes to afford 1,2-N,Si compounds via ligand relay catalysis. A phenomenon of ligand relay is found that the tridentate anionic N-ligand (OPAQ) could capture the cobalt ion from bidentate neutral P-ligand (Xantphos) cobalt complex This protocol uses three abundant chemical feedstocks, alkynes, silanes, and diazo compounds, and features operationally simple, mild conditions, low catalyst loading (1 mol%), and excellent functional group tolerance. Our group is quite interested in earth-abundant transitionmetal-catalyzed reactions of alkenes and alkynes[11–15,34–37], here, we report a cobalt-catalyzed chemo- and regioselective sequential hydrosilylation/hydrohydrazidation of terminal alkynes via ligand relay catalysis with hydrosilanes and diazo compounds to afford vicinal amino and silyl products bearing both N-H bond and Si-H bond which could be further derivatized (Fig. 2b)
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