METHYLATION OF THE BETA-POSITIONS OF THE FURAN RING IN F-ACIDS

Major incubation products in feeding experiments with the sodium salt of 7-(5-butyl-furan-2-yl)heptanoic acid (3) on suspension cultures of Saccharum spec, are the unusual F-acids (4a) and (4b). They possess in contrast to natural monomethyl substituted F-acids a methyl substitue nt in the 4-position of the furan ring. Unexpectedly, the dimethyl sub stituted F-acids (4c) and (4d) were found only in very small amounts. The detection and structure elucidation of the methylation products (4 a)-(4d) was achieved predominantly by GC-MS analysis of the correspond ing tetrahydrofuran derivatives (5a)-(5d).