tetrahydroanthraquinones bearing an amido group have been prepared by Diels-Alderreactions between (E)-1-(N-carbobenzyloxyamino)-1,3-butadiene (2) or (E)-1-(N-benzoyl-N-benzylamino)-1,3-butadiene (5) and benzoquinone or 5-substituted naphthoquinones. The stereochemistry of the cycloadditions was investigated. A high regioselectivity was observed in the reaction of the diene carbamate 2 with 5-methoxy and 5-acetoxy
Process for preparing amino- and carbamoyl-substituted anthraquinones by Diels-Alder reaction of an N-butadienylcarbamic acid ester of the formula H.sub.2 C.dbd.CH--CH.dbd.CH--NH--COOR.sup.2, wherein R.sup.2 is alkyl or phenylalkyl, with a 1,4-naphthoquinone or with 1,4-benzoquinone to form a carbamoyl-substituted hydroanthraquinone intermediate and by oxidation of this intermediate with an oxygen-containing gas in a tertiary amine and in the presence of a copper salt to obtain a carbamoyl-substituted anthraquinone product. The Diels-Alder reaction and the oxidation reaction can be carried out as a one-pot synthesis or in separate steps. The carbamic acid ester reactant provides a blocking group represented by --COOR.sup.2, and this blocking group is optionally removed by treatment of the carbamoyl-substituted anthraquinone with an alkaline hydroxide solution.