The synergistic copper/ppm Pd-catalyzed hydrocarboxylation of alkynes with formic acid as a CO surrogate as well as a hydrogen source: an alternative indirect utilization of CO

An unprecedented strategy has been developed involving the earth-abundant Cu-catalyzed hydrocarboxylation of alkynes with HCOOH to ( E )-acrylic derivatives with high regio- and stereoselectivity via synergistic effects with ppm levels of a Pd catalyst. Both symmetrical and unsymmetrical alkynes bea...

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Published in:Green chemistry : an international journal and green chemistry resource : GC 2021-10, Vol.23 (2), p.889-895
Main Authors: Xia, Shu-Mei, Yang, Zhi-Wen, Yao, Xiang-Yang, Chen, Kai-Hong, Qiu, Li-Qi, He, Liang-Nian
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Summary:An unprecedented strategy has been developed involving the earth-abundant Cu-catalyzed hydrocarboxylation of alkynes with HCOOH to ( E )-acrylic derivatives with high regio- and stereoselectivity via synergistic effects with ppm levels of a Pd catalyst. Both symmetrical and unsymmetrical alkynes bearing various functional groups were successfully hydrocarboxylated with HCOOH, and the modification of a pharmaceutical molecule exemplified the practicability of this process. This protocol employs HCOOH as both a CO surrogate and hydrogen donor with 100% atom economy and it can be viewed as an alternative approach for indirect CO 2 utilization. Mechanistic investigations indicate a Cu/ppm Pd cooperative catalysis mechanism via alkenylcopper species as potential intermediates formed from Cu-hydride active catalytic species with HCOOH as a hydrogen source. This bimetallic system involving inexpensive Cu and trace Pd provides a reliable and efficient hydrocarboxylation method to access industrially useful acrylic derivatives with HCOOH as a hydrogen source, and it provides novel clues for optimizing other Cu-H-related co-catalytic systems. Dual Cu/ppm Pd catalysis is established that enables highly efficient hydrocarboxylation of alkynes with HCOOH as the hydrogen source and CO surrogate via copper hydride, to deliver various ( E )-acrylic derivatives.
ISSN:1463-9262
1463-9270
DOI:10.1039/d1gc02735b