... Tetrahedron. Volume 40, Issue 22, 1984, Pages 4597–4607. ... The cyanophthalide 32 the CD half of the molecule, is attached with good regiocontrol and a subsequent tetracyclic C6-C7 acetonide 40, oxygenated a C-9 to eventually produce a 5:6 mixture 1 and its C-7 epimer 8. ...