Platinum(II) Enyne Cycloisomerization Catalysis: Intermediates and Resting States.
In situ generated [(PPP)Pt][BF(4)](2) (PPP = triphos) catalyzes the cycloisomerization of 1,6-enyne-ols by initiative pi-activation of the alkyne. This generates an isolable cationic Pt-alkenyl species which subsequently participates in turnover limiting protonolysis with in situ generated acid. This latter reactivity contrasts cationic Pt-alkyls which are more difficult to protonolyze. Mechanistic studies on isolated Pt-alkenyls, and deuterium labeling helped to elucidate the mechanistic details.
Nelsen
D Luke
DL
Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290.
Gagné
Michel R
MR