were obtained in the i-PrLi/CO/Me3SiC1 reaction, which produced MezCHC (0) SiMe3 in 28% yield. It is clear that the complications of the two-step procedure have not been avoided entirely by using the in situ procedure. However, for the synthesis of acyltrimethylsilanes containing primary alkyl groups and of pivaloyltrimethylsilane, the in situ procedures can be used to good advantage: the reactions are fairly clean and they give satisfactory yields of ...