SYNTHESIS OF 4-SUBSTITUTED TETRONIC ACIDS: MULTICOLANIC ACID

Multicolanic acid (3), and other 4-substituted tetronic acids (8), (9), (10), and (17) are conveniently synthesised from the corresponding unsubstituted parent compounds by protection of the enolic hydroxy-groups with pyrrolidine, and reaction of the carbanions of the resultant derivatives with either alkyl halides or aldehydes, followed by acid catalysed removal of the protecting groups.