DIRECTED METALLATIONS OF 4-ETHYLIDENETERONIC ACID AND ITS DERIVATIVES AS A SYNTHETIC ENTRY TO NATURAL 4-OXY-2-FURANONES

Article abstract of DOI:10.1016/S0040-4039(00)86896-3

Lithium diisoprpylamide (LDA) removes the α-proton from the O-methyl tetronic acid (2b) leading to the vinylic carbanion (12), whereas treatment of the trimethylsilyl derivative (14) with LDA, followed by reaction with aldehydes gives products resulting from both γ- and ε-addition; the directed metallations provide access to a range of 4-oxy-2-furanone derivatives found amongst natural products.