Total synthesis of muamvatin.

Enantioselective total synthesis of muamvatin was achieved by ring-chain tautomerization of an acyclic derivative assembled by sequential substrate-controlled stereoselective aldol reactions of a chiral ketone with two achiral aldehydes. Although the trioxaadamantane tautomer was shown to be thermodynamically more stable than alternative forms, the kinetic barrier to cyclization was significant. This observation raises doubts about the proposed formation of muamvatin as an artifact of isolation.