(3R,4R)-3-[(1S)-1-hydroxyalkyl]-4-(hydroxymethyl)oxolan-2-one
(3r,4r)-3-[(1s)-1-hydroxyalkyl]-4-(hydroxymethyl)oxolan-2-one
A butan-4-olide in which the lactone skeleton is substituted at positions 3<em>pro</em>-<i>R</i> and 4<em>pro</em>-<i>R</i> by 1-hydroxyalkyl and hydroxymethyl groups, respectively, in which the secondary alcohol has moiety has <i>S</i> configuration. Originally isolated from <em>Streptomyces virginiae</em>, where they control virginiamycin production, they are also known as virginiae butanolides (VB compounds).