N-Functionalized Ferrocenes: Subvalent Group XIV Element Chlorides and tert-Butyllithium-Induced C-C Bond Cleavage under Mild Conditions.

The ferrocene derivative (η5 -Cp)Fe{η5 -C5 H3 -1-(ArNCH)-2-(CH2 NMe2 )} (1; Ar=2,6-iPr2 C6 H3 )) reacts diastereoselectively with LiR by carbolithiation and subsequent hydrolysis to give (η5 -Cp)Fe{η5 -C5 H3 -1-(ArHNCHR)-2-(CH2 NMe2 )} (3: R=tBu; 4: R=Ph; 5: R=Me) in high yields. For R=tBu, the organolithium derivative (η5 -Cp)Fe{η5 -C5 H3 -1-(ArLiNCHR)-2-(CH2 NMe2 )} (2) was isolated. Compound 2 reacts with GeCl2 ⋅dioxane and SnCl2 to give the metallylene amide chlorides (η5 -Cp)Fe{η5 -C5 H3 -1-(ArMNCHtBu)-2-(CH2 NMe2 )} 6 (M=GeCl) and 7 (M=SnCl), respectively, which each contain three stereogenic centers. The potential of 7 as a ligand in transition-metal chemistry is demonstrated by formation of its complex (η5 -Cp)Fe{η5 -C5 H3 -1-(ArMNCHtBu)-2-(CH2 NMe2 )} [9, M= Sn(Cl)W(CO)5 ]. Treatment of 3 with tert-butyllithium at room temperature causes an unprecedented carbon-carbon bond cleavage whereas under kinetic control, lithiation at the Cp-3 position takes place, which leads to the isolation of (η5 -Cp)Fe{η5 -C5 H3 -1-(ArHNCHtBu)-2-(CH2 NMe2 )-3-SiMe3 } (10).