Atropisomerism of the C-1-C'-1 axis of 2,2',8,8'-unsubstituted 1,1'-binaphthyl derivatives.

ABSTRACT

The Suzuki coupling of optically active (S)-binaphthyl bromide 10 with (S)-binaphthyl boronic acid 11 produced a diastereomeric mixture of tetrahydroxyquaternaphthyls 4. The coupling products 4as well as their derivatives 5-7 can be considered as members of the family of 1,1'-binaphthyl-3,3'-diols. The C-1-C'-1 axis of all these compounds was found to have an unusually high rotational barrier. Generally, the barrier is higher for derivatives having more bulky substituents at the 3 and 3' positions.