• Reagent, introduced by Yamaguchi, which forms mixed anhydrides with acids, useful in the synthesis of esters: Bull. Chem. Soc. Jpn., 52, 1989 (1979), or lactones including macrolides: Chem. Lett., 1021 (1979). Superior to mesitylenesulfonyl chloride for macrolactonization, which has been achieved in the presence of DMAP without the need for high dilution: J. Org. Chem., 55, 7 (1990); Tetrahedron Lett., 31, 6367 (1990).