STRUCTURE AND MICROBIOLOGICAL ACTIVITY IN THE ENNIATIN-SERIES

Publisher Summary This chapter discusses the structure of and microbiological activity in the Enniatin-series. The cyclic depsipeptide is built up by regularly alternating D-α-hydroxyisovaleric acid and a N-methyl-amino-acid, which in Enniatin A is N-methyl- L-isoleucine and in Enniatin B N-methyl- L-valine. The tertiary butyl ester of D-α-hydroxy-isovaleric acid is coupled by means of benzene sulfochloride to the corresponding benzyloxycarbonyl-amino-acid in the presence of pyridine. By enlarging the decarbobenzoxylated tetradepsipeptide ester used in the Enniatin B synthesis with the didepsipeptide acid containing L-valine, the hexadepsipeptide for the monodesmethyl-product can be obtained. The synthetic route to the tridesmethyl-enniatin B resembles the one used for the synthesis of the Enniatin B, differing only by the use of L-valine instead of N-methyl- L-valine.