Total synthesis of xanthohumol.

The total synthesis of xanthohumol (1) was accomplished in 10% overall yield from phloracetophenone after six steps. Insertion of a prenyl group onto the aryl ring was achieved by a para-Claisen rearrangement after using a Mitsunobu reaction to establish the key prenyl ether precursor. A Claisen-Schmidt condensation was deployed to construct the chalcone scaffold followed by removal of MOM protecting groups under acidic conditions that were optimized to prevent concomitant cyclization to the flavone.