Selective Construction of C-C and C=C Bonds by Manganese Catalyzed Coupling of Alcohols with Phosphorus Ylides

Herein, we report the manganese catalyzed coupling of alcohols with phosphorus ylides. The selectivity in the coupling of primary alcohols with phosphorus ylides to form carbon-carbon single (C-C) and carbon-carbon double (C=C) bonds can be controlled by the ligands. In the conversion of more challenging secondary alcohols with phosphorus ylides the selectivity towards the formation of C-C vs. C=C bonds can be controlled by the reaction conditions, namely the amount of base. The scope and limitations of the coupling reactions were thoroughly evaluated by the conversion of 21 alcohols and 15 ylides. Notably, compared to existing methods, which are based on precious metal complexes as catalysts, the present catalytic system is based on earth abundant manganese catalysts. The reaction can also be performed in a sequential one-pot reaction generating the phosphorus ylide in situ followed manganese catalyzed C-C and C=C bond formation. Mechanistic studies suggest that the C-C bond was generated via a borrowing hydrogen pathway and the C=C bond formation followed an acceptorless dehydrogenative coupling pathway.

Automated summary

The manganese catalyzed coupling of alcohols with phosphorus ylides was found to be controllable in terms of selectivity for forming carbon-carbon single and double bonds by adjusting ligands and reaction conditions. Compared to previous methods using precious metal complexes, this system utilizes earth abundant manganese catalysts, allowing for C-C and C=C bond formation in a sequential one-pot reaction. Mechanistic studies revealed that C-C bonds were generated through a borrowing hydrogen pathway, while C=C bond formation followed an acceptorless dehydrogenative coupling pathway.