(16) Klein, H.; Steinmetz, A. Tetrahedron Lett. 1975, 4249. (17) This is the expected percentage of malyngolide in the malyngo- lide-epimalyngolide mixture, not the diaatereomeric excess. (18) We thank Professor T. Mukaiyama for supplying u8 with proton NMR spectra of (-)-malyngolide and (+)-epimalyngolide. (19) The fact that the calculated and found percentages of epimeric impurities agreed within experimental error in all four cases is an indi- cation that no ...