Intramolecular endo-dig hydrosilylation catalyzed by ruthenium: evidence for a new mechanistic pathway.
The ruthenium catalyst [Cp*Ru(MeCN)3]PF6 effects a novel intramolecular hydrosilylation of homo- and bis-homopropargylic alcohols, producing products of unique regioselectivity under very mild conditions with excellent selectivity. The reaction is compatible with a wide range of functional groups and tolerates substantial steric bulk. In addition to producing valuable synthetic intermediates thus far obtainable only in circuitous fashion, the results imply the necessity for a reexamination of the mechanism surrounding trans-hydrosilylation reactions, at least for ruthenium catalysts. At the very least, a simple cis addition/isomerization mechanism almost certainly cannot be active in this case. A silicon-ruthenium transposition could potentially provide a rationalization. However, the evidence for any products of syn addition with nonhydrido ruthenium catalysts is very scarce. Alternatively, a direct trans addition to orthogonal p-systems is also a possibility.
Trost
Barry M
BM
Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA. bmtrost@stanford.edu
Ball
Zachary T
ZT
D000480:Alkynes / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D009942:Organometallic Compounds / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry*; D012821:Silanes / Q000138:chemical synthesis* / Q000737:chemistry; D014753:Vinyl Compounds / Q000138:chemical synthesis* / Q000737:chemistry
D000480:Alkynes; D009942:Organometallic Compounds; D012821:Silanes; D014753:Vinyl Compounds; D012428:Ruthenium