Synthesis of 2,3,6,7,8,9-Hexahydro-1 H -cyclohepta[ gh ]phenalene

2,3,6,7,8,9-Hexahydro-1H-cyclohepta[gh]phenalene (7) has been prepared via the tricyclic ketone 3-oxo-1,2,3,7,8,9,10,10a-octahydrocyclohepta[de]naphthalene (1) and the tetracyclic ketone 1-oxo-2,3,6,7,8,9-hexahydro-1H-cyclohepta[gh]phenalene (6). Conversion of the tricyclic ketone 1 into 1-oxo-1,2,3,3a,5,5a,6,7,8,9-decahydro-4H-cyclohepta[cd]phenalene (8) and reduction of this tetracyclic ketone to 1,2,3,3a,5,5a,6,7,8,9-decahydro-4H-cyclohepta[cd]phenalene (9), followed by aromatization, gave 5,5a,6,7,8,9-hexahydro-4H-cyclohepta[cd]phenalene (10) (73 %) together with the desired isomeric 2,3,6,7,8,9-hexahydro-1H-cyclohepta[gh]phenalene (7) (23%).