Oligomerisation of alkynes at a pentamethylcyclopentadienylruthenium centre
†
Abstract
Reactions between the neutral vinylidene RuCl(C
CHPh)(PPh3)Cp*
2 and AgC
CCO2Me gave Ru{η1-C(C
CPh)
CHC(O)OMe-O
}(PPh3)Cp*
3, while either LiC
CPh or HC
CPh/NaOMe afforded the known Ru{η3-PhCHCHC
CPh(C
CPh)}(PPh3)Cp*
1. Similarly, RuCl{
C
CH(CO2Me)}(PPh3)Cp*
4 reacted with HC
CPh/NaOMe to give Ru{η3-CH(CO2Me)CHC
CPh(C
CCO2Me)}(PPh3)Cp*
5. Complex 3 reacted with HC
CCO2R (R = Me or Et) to give the 1,3,4,5-tetraen-1-yls Ru{η1,η2-C(CO2R)
CHCPh
C
C
CH(CO2Me)}(PPh3)Cp* (R = Me 6 or Et 7)] and with HC
CSiMe3 to give a mixture of Ru{η3-CH(CO2Me)C(CH
CHSiMe3)C
CPhC
CSiMe3}(PPh3)Cp*
8 and Ru{η3-CH(CO2Me)CHC
CPh(C
CSiMe3)}(PPh3)Cp*
9. Crystal structures of 1, 3 and 5–8 were determined. These reactions provide routes to the stepwise formation of novel non-cyclic oligomers of 1-alkynes, with 8 containing the first example derived from four