New fluorescent trans-dihydrofluoren-3-ones from aldol-Robinson annulation-regioselective addition involved one-pot reaction.

An unexpected discovery of new trans-4-acetyl-1,9-dimethyl-4,4a-dihydro-3H-fluoren-3-ones from one pot reactions of benzaldehydes and acetylacetone is described. The synthetic mechanism and stereochemistry were discussed. These new derivatives exhibit good fluorescent properties in solutions.