Nguyen TT.
Koh MJ.
Mann TJ.
Schrock RR.
Hoveyda AH.
* Boston College, and Massachusetts Institute of Technology, Cambridge, USA
Synthesis of
E- and
Z-Trisubstituted Alkenes by Catalytic Cross-Metathesis.
Nature 2017;
552: 347-352
Key words
olefin metathesis - molybdenum catalysis - alkenyl halides
Significance
Crossed olefin metathesis is a challenge in organic chemistry because of the prevalence
of side reactions from homo-metathesis. Hoveyda and co-workers report a crossed metathesis
with high E/Z-selectivity generating trisubstituted haloalkenes. The reaction shows good to excellent
E/Z-selectivity and can generate either the E or Z product depending on the stereochemistry of the starting olefin.
Comment
Alkenyl chloride products could be generated in good to excellent yields wherein the
trans product was formed with higher E/Z ratios. Additionally, the alkenyl bromide products could be generated. The improved
selectivity for the trans-olefin starting material was explained with the stereochemical model. In the case
of the Z-olefin, the energy gap between the two potential pathways is less because steric
repulsion is significant in both pathways, leading to lower E/Z ratios.
