The Total Synthesis of (−)-SNF4435 C and (+)-SNF4435 D

The size and positioning of substituents on a tetraene, along with the Woodward−Hoffmann rules, control the relative stereochemistry at the four adjacent chiral centers that are generated in the 8π/6π electrocyclization cascade. A biomimetic synthesis of (−)-SNF4435 C and (+)-SNF4435 D exploits these steric effects and allows confirmation of the predicted absolute stereochemistry of the natural products.