Spiro[4,4]-1,6-nonadiene-based diphosphine oxides in lewis base catalyzed asymmetric double-aldol reactions.

Symmetry swap: A C2 -chiral spiro diphosphine oxide (SpinPO) has been found to be highly efficient and enantioselective in the catalysis of double-aldol reactions of ketones and aldehydes to give the corresponding optically active double-aldol products, which can be readily transformed into optically active C3 - and pseudo-C3 -symmetric molecules.