Quinone epoxides. Part VII. Stereospecific elaboration of 2-acetyl-1,4-naphthoquinone epoxides

Abstract

The reductive elaboration of 2-acetyl-3-methyl-1,4-naphthoquinone epoxide has been examined in an investigation into the potential of quinone epoxides as intermediates in the stereospecific syntheses of alicyclic compounds from aromatic starting materials. A series of products is obtained by stereospecific and selective reduction with borohydride; these are further transformed stereospecifically. Direct reductive opening of the epoxide ring has not been achieved. Catalytic reduction of the bromohydrin (XIV) obtained in these transformations is stereospecific but not selective. Catalytic reduction of the 3-acetyl-3,4-dihydroxy-2-methyltetralone (XVI) also leads to a mixture of products, one of which undergoes ring expansion under mild conditions to form the benzocycloheptenone derivative (XXVII).