A chiral C-2 axially symmetric naphthalene derivative of a bicyclooctane diketal

The crystal structure of the title compound, (-)-(4R,5R,-4''R,5''R)-dispiro [4,5-dimethyl-1,3-dioxalane-2,3'- [1',5' -(naphthalene-1,8-diyl)bicyclo[3.3 .0]octane]-7',2''-(4'',5''-dimethyl-1'',3''-dioxalane)], C26H30O4, contains two independent molecules in the asymmetric unit separated by normal van d er Waals distances. The five-membered rings in the trans-2,3-dimethyl-1,4-d ioxaspiro[4.4]nonane moieties exhibit envelope conformations and the acenap hthene moieties are essentially planar. The conformations of a dioxacyclope ntane ring in the two molecules are different. The molecular dimensions in both molecules are as expected.