Enantioselective Synthesis Muqubilin and Negombatoperoxides B and C/D

Muqubilin, negombatoperoxide B, and negombatoperoxide C/D were synthesized through enantioselective routes, with the quaternary center derived from a peroxy chiral building block of known absolute configuration. The C-2/C-3 stereogenic centers were introduced by asymmetric aldol condensation, and the 1,2-dioxane ring was constructed via an intramolecular alkylation of a hydroperoxide with a mesylate. The synthetic samples showed physical and spectroscopic data consistent with those reported in the literature and thus verified the configurations of the natural products. A potentially more expeditious enantioselective entry to the 1,2-dioxane-aldol moiety (C-1 to C-6) of such cyclic peroxides was also briefly explored, where the C-2/C-3 stereogenic centers were installed through a [2+2] cycloaddition and the 1,2-dioxane ring was closed via an intramolecular alkylation coupled with an alkyl-oxygen cleavage of a β-lactone.