Synthesis of tetrahydroanthracen-9-ones by the domino aldol condensation/Diels–Alder cycloaddition

A facile protocol toward several substituted 3-aryl-3,4,4a,10-tetrahydro-2H-anthracen-9-ones 1 starting with substituted 2-allylbenzaldehydes 2 was described. The overall synthetic process was carried out by the domino aldol condensation/Diels–Alder cycloaddition of skeleton 2 with substituted cinnamaldehydes 3 in an alkalic aqueous-methanolic solution followed by base-induced double migration of the resulting cycloadducts. Skeleton 2 was prepared from isovanillin (4) in moderate yield in five-steps via the known procedures with the synthetic sequence of O-allylation, Claisen rearrangement, O-methylation, Grignard methylation, and PCC-mediated oxidation.