Two polycyclic compounds derived from a Diels-Alder reaction

In both 9,10-dimethoxy-11-oxatricyclo[6.2.1.0(2,7)]undeca-4,9-diene-3,6-diol, C(12)H(16)O(5), (I), and 5,6-dimethoxy-3,7-dioxatetracyclo[6.4.0.0(2,6).0(4,12)]dodec-9-en-11-ol, C(12)H(16)O(5), (II), the hetero-oxygen-containing five-membered rings have an envelope conformation. The six-membered rings are in a boat conformation in compound (I), and in (II), one is in a half-boat and the other is in a slightly distorted boat conformation. The molecules in both compounds interact through classical hydrogen bonds and C-H.O contacts.