Palladium-catalyzed cross-coupling of terminal alkynes with 4-trifloyloxazole: Studies toward the construction of the C26-C31 subunit of phorboxazoleA

[GRAPHICS] A strategy has been developed that successfully takes advantage of transiti on-metal-catalyzed coupling reactions for the synthesis of highly functiona lized oxazoles. Trifloyloxazoles have been used as coupling partners with a lkyne-derived vinylmetallic intermediates in Stille- and Negishi-type coupl ings to assemble the corresponding oxazoles in good isolated yield. The res ults obtained provide a close analogy and thus good precedent to employ thi s strategy in the synthesis of the oxazole subunits of phorboxazole A.