Synthesis and antileishmanial activity of the core structure of cristaxenicin A.

The core structure of cristaxenicin A having trans-fused dihydropyran and nine membered ring has been synthesized and evaluated the antileishmanial activity. The dihydropyran ring was synthesized by [4+2] cycloaddition reaction between an unsaturated aldehyde and a β-alkoxy-α,β-unsaturated ketone. The nine membered ring possessing α,β-unsaturated aldehyde was constructed by the intramolecular NHK reaction followed by the Mitsunobu rearrangement.