Tandem polycyclization-Pinacol process

A tandem polycyclization-Pinacol process has been developed using a similar strategy as described above. As shown in Scheme 29, the polyfunctionahzed phenol 100 is transformed into the compound 104 when treated with [bis(trifluoroacetoxy) iodo]benzene in a mixture of hexafluoroisopropanol and dichloromethane [25]. The reaction occurs through a succession of chair-Uke transition states, in which the phenoxenium ion 101 is first trapped by the endocychc alkene to deliver the intermediate 102, which then reacts with the alkyne to produce cation 103. The process concludes with a pinacol-like ring contraction. The presence of a chlorine... 

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