Cobalt(I)‐Catalyzed E‐Selective Hydroalkynylation of Terminal Alkynes or Internal Alkynes with Silyl‐Substituted Terminal Alkynes

The cross-hydroalkynylation of silyl-substituted terminal alkynes, acting as CH-donor alkynes, with aryl- or alkyl-substituted terminal alkynes, acting as acceptor alkynes, is described. Cross-hydroalkynylation with internal alkynes acting as acceptor alkynes is successful when at least one aryl substituent is present. The reaction optimization is performed by the Design of Experiments approach, limiting the needed test reactions to a minimum.

A stereoselective cross-dimerization between silyl-substituted donor alkynes and aryl- or alkyl-substituted terminal acceptor alkynes using an in situ generated Co(I)-phosphine catalyst is reported. The reaction optimization for both classes of acceptor alkynes is conducted via Design of Experiments and showed high E-selectivities using different reaction conditions. Moreover, activated internal alkynes are successfully applied as acceptor alkynes in the cross-hydroalkynylation, leading to highly substituted 1,3-enynes in good regioselectivities and good to excellent yields.

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