Other Li-Barbier Reactions with Sterically Hindered Reagents

8 Other Li-Barbier Reactions with Sterically Hindered Reagents 1988 

As shown earlier, Li-Barbier reactions are very effective in the synthesis of sterically crowded alcohols (pp. 86-90). 

However, little success was met in the one-step synthesis of l-(2-adamantyl)-2-methyl-2-phenyl-l-ethanol from 2-chloro-2-phenylpropane, adamantanone and lithium in tetrahydrofuran [36]. But when this reaction was run in the presence of a catalytic amount (1-3 mol%) of the aromatic electron-transfer agent 4,4 -di-tm-butylbiphenyl (DBB), the desired tertiary alcohol was obtained in 67% yield  

No such catalyst was required for the synthesis of a carbocychc analogue of quercetin with the same type of sterically crowded benzylic halide (A) [37]  

Attempts to prepare the organolithium compound prior to coupling with the aldehyde, failed. 

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