Cyclodecane: transannular strain

As was indicated in Table 3.6 (p. 95), cyclodecane is significantly more strained than cyclohexane. Examination of the boat-chair-boat conformation reveals that the source of most of this strain is the close van der Waals contacts between two sets of three hydrogens on either side of the molecule. The hydrogens involved are shown in the drawing. Distortion of the molecule to twist forms to relieve this interaction introduces torsional strain. It seems reasonable to assume that suitably substituted cyclodecanes may be found in which the transannular van der Waials repulsion is sufficiently large to allow a conformation other than the boat-chair-boat to be the most stable. 

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