Optically active spiro[4.4]nonane derivatives: syntheses and circular dichroism of homoconjugated dienes and diketimine derivatives

Abstract

(+)-(5S)-Spiro[4.4]nona-1,6-diene (1), (+)-(5S)-6-methylenespiro[4.4]non-1-ene (2), (+)-(5R)-1,6-dimethylenespiro[4.4]nonane (4), and four diketimine derivatives from (-)-(5S)-spiro[4.4]nonane-1,6-dione (5) were prepared; their chiroptical behaviour in the π→π* region was consistent with expectations based on the exciton model, except for (1).