A trans-semihydrogenation of 1,3-enynes with ethanol as the hydrogen source was developed using a new (PCN)Ir complex as the precatalyst and tBuNH2 as the cocatalyst. This catalyst system provides an… Click to show full abstract
A trans-semihydrogenation of 1,3-enynes with ethanol as the hydrogen source was developed using a new (PCN)Ir complex as the precatalyst and tBuNH2 as the cocatalyst. This catalyst system provides an efficient and atom-economical access to unsymmetrical (E,E)-1,4-diarylbutadienes with high yields and stereoselectivities. Monitoring the process revealed that a sequence of cis-semihydrogenation of the triple bond of 1,3-enynes (to form (E,Z)-butadienes) and (E,Z)-to-(E,E) isomerization occurs to form (E,E)-butadienes.
               
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