A shortcut to the smaller fragment of pamamycin-607

Starting from a key intermediate for the synthesis of the larger hydroxy acid constituent of pamamycin-607 (1), an efficient three-step route to the methyl ester of the smaller fragment of 1 involving a Yamaguchi lactonization with concomitant C(2) epimerization was developed. Alternatively, the methyl ester of the smaller hydroxy acid portion of 1 was prepared by direct C(2) epimerization.