Abstract
The total synthesis of (+)-methyl phaseate (2b) and its epimer (25) is described. The known β-ketoester (8), which was prepared from (-)-β-pinene (4), was converted to a key intermediate (5) via a 1, 4-dioxoester (7). The reaction of 5 with a lithium reagent of the acetylene TBDMS ether (6) in THF-HMPA at -70°C afforded the desired acetylene alcohol (17) and its epimer (18) in high yields. 17 was transformed into (+)-methyl phaseate (2b). From this synthetic work, the absolute configuration of natural (-)-phaseic acid (2a) was confirmed.
