A stereo- and enantioselective approach to clavulones from tricyclodecadienone using flash vacuum thermolysis

Article abstract of DOI:10.1016/0040-4020(95)00237-3

The stereo- and enantioselective synthesis of clavulones 6 and their analogues 48 is described. γ-Hydroxycyclopentenones (-)-13 and 44, which are key intermediates in this approach, are obtained from enantiopure endo-tricyclo[5.2.1.0^2,6]decadienones (+)-14 and (+)-20 in 6 and 8 steps, respectively. Crucial steps are the reductive epoxy ring opening in compounds (+)-25 and 39 to give the corresponding diols (+)-27 and 40, and the thermal cycloreversion of tricyclodecenones (+)-27 and 41, using the technique of flash vacuum thermolysis (FVT). The synthesis of enantiopure (-)-13 represents a formal total synthesis of clavulones 6. The synthesis of vlavulone analogues (-)-48E and (-)-48Z (X = CH₂OH) is completed by condensation of 44 with aldehyde 45 followed by elimination of water and removal of the protective THP-group.