Synthesis of Streptovitacin-C2 Isomers

(2R*,4S*,6S*,αS*)- and (2R,4R,6R,αS)-Streptovitacin-C₂ (STV-C₂) (1a and 1b) were synthesized by an aldol condensation of (2R*,4S*)- or (2R,4R)-2,4-dimethyl-2-trimethylsiloxy-1-cyclohexanone (15a or 15b) with 4-(2-oxoethyl)-2,6-piperidinedione (16), which was followed by desilylation of the products. The stereochemistry of the synthesized STV-C₂ isomers (1a and 1b) was elucidated by NMR. STV-C₂ isomers (1a and 1b) did not show strong antimicrobial activity against Saccharomyces cerevisiae and Pyricularia oryzae.