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Diastereoselective Total Synthesis of Both Enantiomers of Epolactaene

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journal contribution
posted on 05.12.2002, 00:00 by Yujiro Hayashi, Jun Kanayama, Junichiro Yamaguchi, Mitsuru Shoji
A stereocontrolled total synthesis of both the (+)- and (−)-epolactaene ((+)- and (−)-1) enantiomers from tetrahydropyran-2-ol is described. The following reactions in this synthesis are particularly noteworthy:  (1) the stereoselective construction of the conjugated (E,E,E)-triene by a combination of kinetic deprotonation and thermodynamic equilibration, (2) the E-selective Knoevenagel condensation of β-ketonitrile 33 with a chiral 2-alkoxyaldehyde, (3) a diastereoselective epoxidation achieved using a bulky nucleophile (TrOOLi) and an appropriate protecting group, (4) the mild hydrolysis of an α-epoxy nitrile by silica gel on TLC facilitated by hydroxyl-mediated, intramolecular assistance.