Total synthesis of (-)-hennoxazole A

The antiviral marine natural product (-)-hennoxazole A was efficiently synt hesized by a convergent approach. The stereoselective synthesis of the func tionalized tetrahydropyran fragment was accomplished by the Mukaiyama aldol reaction, chelation-controlled 1,3-syn reduction, Wacker oxidation, and ac id catalyzed intramolecular ketalization. The nonconjugated triene fragment was synthesized by S(N)2 displacement of an allylic bromide with vinyllith ium and the CrCl2-mediated iodoolefination followed by palladium-catalyzed cross coupling with MeMgBr. The final steps include the fragment coupling u sing DEPC and oxazole synthesis via an oxidation/cyclodehydration process. (C) 2001 Elsevier Science Ltd. All rights reserved.