Sulfones, 7,7-dimethylallenyl phenyl

Treatment of a solution of y,"y-dimethylallenyl phenyl sulfone with one-half equivalent of -butylli-thium at 0 C results in dimerization of the substrate. However, if the same reaction is carried out at reflux temperature for 6 h, the cyclodimer is obtained (Scheme 25). ... 

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