The spiro ketals, Figs. 1 and 2, are chiral, enantiomers of one another. ... These compounds have only two identical groups proximate to the spiro carbon: oxygen and CH2.
Are all spiro compounds chiral?
Assignment of absolute configuration of spiro compounds has been challenging, but a number of each type have been unequivocally assigned. Some spiro compounds exhibit axial chirality. Spiroatoms can be the origin of chirality even when they lack the required four different substituents normally observed in chirality.
Are spiro compounds aromatic?
Spiro polycyclic aromatic compounds consist of two π-conjugated systems that are perpendicularly fixed by an sp3-hybridized spiro atom. They have been widely studied and used as organic functional materials, because of their unique properties.
