[reaction: see text] Beginning with D-mannitol, a stereoselective synthesis of the right-half segment of the mycalamides has been accomplished by employing Lewis acidcatalyzedintermolecularaldolreaction and oxypalladation as the key steps.
A convergent total synthesis of (+)-mycalamide A is described. A Yb(OTf)(3)-TMSCI catalytic system is used to synthesize a trioxadecalin ring system, which contains the right segment of mycalamide A. In addition, a tetrallydropyran ring, which is the left segment, is constructed with use of a novel one-pot delta-lactonization protocol. Both segments are prepared from a common starting material, D-mannitol. These segments are then coupled and the functional groups are transformed to synthesize (+)-mycalamide A.