The preparation of three analogues of the putative diketide biosynthetic precursor (2) and eight analogues of the putative triketide biosynthetic precursor (3) of the acyl tetronic acid ionophore tetronasin, as N-acetylcysteamine thioesters (4),(5),(6),(12),(13),(14),(15),(22),(23 ),(24) and (25) is described. Five examples are 19F-labelled; a new, enantiospecific method for the creation of a fluorinated quaternary α-centre is presented.