Crystal structures of 2,4,9-trimethyl-(3ar,4c,9c,9ac)-3a,4,9,9a-tetrahydrobenzo[f]isoindole-1,3-dione(endo), C15H17NO2 (1), and 2-methyl-(3ac,9ac)-3a,4,9,9a-tetrahydro-4r,9c-ethanobenzo[f]isoindole-1,3-dione(endo), C15H15NO2

The title compd. 1 is triclinic, space group P1, with a 7.198(2), b 7.965(2), c 12.707(2) Å, α 72.05(1), β 87.65(2), γ 65.18(2)° ; the title compd. 2 is orthorhombic, space group and Pbca, with a 8.156(3), b 13.177(3), c 22.742(4) Å. The chiral centers in both compds. C3a, C4, C9, C9a are either R, S, R, S or S, R, S, R (compd. 1) and either R, R, S, S or S, S, R, R (compd. 2) because of the centric space group