Total Synthesis and Stereo-chemistry of Pinnatoxins B and C

Pinnatoxins B and C were synthesized from diols (34 R )-3b and (34 S )-3a, respectively, in a stereochemically controlled manner. Through extensive analysis of the 1 H NMR spectra of synthetic PnTXs B and C, the diagnostic NMR signals were first identified to differentiate (34 S )- and (34 R )-diastereomers and then used to establish the C34 configuration of natural PnTXs B and C as 34 S and 34 R , respectively.