“…20 Therefore, 3 was assigned 1R, 2R, 5S, 6S, 8R, 9S, 10R, 11R, and 12S absolute configuration. Cytosporinols A-C (1-3) are closely related to the known taedolidol, 3 6-epitaedolidol, 3 and punctaporonin C (4), 7-9 all possessing the rare oxatetracyclo[6.3.2.0 1,4 .0 5,13 ]tridecane skeleton, but differ by having different substituents at C-6 (1), C-10 (1-3), and C-11 (3), as well as a tetrasubstituted olefin (1) and a terminal olefin (2). In addition, 1-3 are structurally similar to a synthetic byproduct 5 created in the acid-mediated cyclization of the nonatural enantiomer pestalotiopins, 23,24 but differ in having different configurations for all stereogenic centers and substituents at C-6 and C-11, respectively.…”