Toluenechromium tricarbonyl

Benzenechromium tricarbonyl 390 is deprotonated by BuLi in Et20-THF at -40 °C in a reaction that needs careful control for good yields.346 The product 391 can be silylated to give 392 in 60% yield. Toluenechromium tricarbonyl lithiates non-regioselectively on the ring (but at the benzylic position with Na or K bases). Excess base can lead to polylithiation.347... 

Other arenechromium tricarbonyls. Semmelhack has extended his study of the reactions of carbanions with benzenechromium tricarbonyl to anisole-and toluenechromium tricarbonyl. The distribution of products depends on the particular anion used, but almost complete absence of para-substitution is consistently observed. A preference for meta-substitution over orfAo-substitution is general. 

Benzenechromium tricarbonyl, however, does undergo a Friedel-Crafts acylation. Furthermore, the acylation of toluenechromium tricarbonyl using acetyl chloride and aluminum bromide in carbon disulfide gives ortho, meta-, and para-substituted derivatives in the ratio of 39 15 46. The orientation of substituent groups is much different from that of toluene itself, which mainly yields the / -substituted derivative (92%) and a small amount of the o-substituted derivative (80%). 

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