Recognition of paired gaucheP–gaucheM sequences as the source of the rotational barrier in 2,2′-dimethyl-1,1′-bipiperidines

Abstract

The reported rotational barriers about the N–N bond in meso-4,4′-dialkyl-1,1′-bipiperidines (1) have been attributed through molecular mechanics calculations to a novel central-bond staggered conformation wherein two sets of a g⁺g^– sequence are inescapably locked to generate a novel situation of unusually high energy.