Stereostructure Clarifying Total Synthesis of the (Polyenoyl)tetramic Acid Militarinone B. A Highly Acid-Labile N-Protecting Group for Amides†.

The 5S, 8'R, and 10'R configurations of militarinone B (3), which is a natural product from Paecilomyces militaris, should equal those in its biosynthetic precursor, militarinone C. The configuration at C-1' emerged from syntheses of the militarinone B candidates 1''S- and 1''R-(5S,8'R,10'R)-3 from the building blocks 9, 11, 14, and 15a while introducing TMB as a more acid-labile N-protecting group for β-ketoamides than DMB. Comparisons of 1''S- and 1''R-(5S,8'R,10'R)-3 with natural militarinone B (3; reisolated from Nature) revealed identity versus distinctness.