Optically active spiro[4.4]nonane derivatives: syntheses and circular dichroism of bis-αβ-unsaturated ketones
Abstract
(5S)-Spiro[4.4]nona-3,8-diene-2,7-dione (1) and (5S)-spiro[4.4]nona-2,7-diene-1,6-dione (2) have been prepared; the c.d. of (1) in the longest wavelength π→π* region shows the opposite sign to that predicted by exciton theory as in the case of spiro[4.4]nona-1,6-diene (3).