Ring Inversion in Cycloheptane and in Cycloheptene Derivatives

Abstract

Rapid pseudorotation [I] causes interconversion of substituent groups between "above" and "below" positions in cycloheptanes even at -150º[2] unless restrictions are imposed by bulky groups ^(12b.31). An especially interesting example of cycloheptane conformational preferences and rates of cycloheptane-ring inversion is provided by 4,5-transdibromo-1,1-difluorocycloheptane (m.p. = 52-54 ºC). This substance was prepared from 4-cycloheptenone via several steps.

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