A SIMPLE SYNTHESIS OF METALLOCENE ALDEHYDES FROM LITHIOMETALLOCENES AND NN-DIMETHYLFORMAMIDE - FERROCENE AND RUTHENOCENE ALDEHYDES AND L,L'-DIALDEHYDES

Lithioferrocene, 1,1'-dilithioferrocene, lithioruthenocene and 1,1'-di lithioruthenocene all react with N,N-dimethylformamide in diethyl ethe r to produce the respective aldehydes. The lithiation of the two metal lacenes can be steered to maximize the formation of only one of the tw o aldehydes by choosing either n-butyllithium in the presence of tetra methylethylenediamine (TMEDA) or t-butyllithium ((t)BuLi) as the metal lating reagent: ferrocene mono-aldehydes or 1,1'-dialdehydes are forme d with good yields (91% and 85% respectively, based on ferrocene), low er yields (50%) of ruthenocene-1,1'-dialdehyde were obtained under the standard conditions, because the 1,3,1'-trialdehyde also formed in si gnificant (19%) amounts. Monolithiation by (n)BuLi and the formation o f the ruthenocene monoaldehyde (yield, 66%) are favoured when TMEDA is used in only catalytic amounts; lithiation of ruthenocene by (t)BuLi selectively leads to monolithioruthenocene and the mono-aldehyde (yiel d, 91%). The products are easily purified by column chromatography. Th e simplicity and the high yield of these reactions make them much more desirable than the previously known multistep procedures.