The distribution of acetate-derived oxygens in the tetronic acids of Penicillium multicolor
Abstract
Incorporation of sodium [1-13C, 18O2]acetate by penicillium multicolor into multicolanic, multicolic, and multicolosic acids(1), (2), and (3), respectively, has given samples which when derivatised and examined by spin echo Fourier transform (S.E.F.T)13C n.m.r. spectroscopy show 18O-induced 13C-satellites, confirming the previously proposed biosynthetic pathway involving oxidative fission of the β-ketide derived intermediate 6-pentylresorcylate (8) and establishing that lactonisation of the tetronic acid ring occurs by displacement from the C-1carboxy-group by the C-4 enolic oxygen, rather than by lactol formation.