Chiral action at a distance: Remote substituent effects on the optical activity of calyculins A and B

[GRAPHICS] Calyculins A and b differ only by the (E) vs (Z) configuration at C(2). Yet , they show a large difference in optical rotations. We demonstrate a new s trategy that provides a physical analysis of this long-range chiro-optical effect by Boltzmann averaged atomic contribution mapping. The polarizabilit y characteristics of the CN substituent rather than the perturbation of the stereogenic centers or the introduction of dissymmetry into the polyene ch ain give rise to the remarkable difference in rotation angles.