Deviation from the anti-Markovnikov rule: a computational study of the regio- and stereoselectivity of diene hydroboration reactions

Abstract

not follow the anti-Markovnikov rule. We proceed to show that in addition to the polarity of the double bonds within a molecule, in this case, the conjugation with the allyl double bond and the specific geometric features of the cyclohexane ring were key stabilizing factors for the unexpected transition state preference, resulting in a regioselectivity that is in quantitative agreement with previous experimental data. Our results further indicated that Re-face attacks and steric factors due to substituents of the substrate influenced mainly the stereoselective outcome of the reaction, also affecting the pathways available to proceed through to complete the hydroboration process.

Rhodium-catalyzed double hydroboration of pyridine: the origin of the chemo- and regioselectivities

“…Such a lack of metal catalytic systems might be due to the kinetic difficulty of the second H[E] addition into the cyclic alkenyl unit of the 1,2- or 1,4-dihydropyridine intermediates. 8 Being aware of the wealth of rhodium hydride reduction chemistry that generally involves the inner-sphere migratory insertion of unsaturated units ( e.g. alkenes) into the Rh–H bond, 9 the Rh catalyst examined by Suginome caught our attention as a potential catalyst for unprecedented double hydroboration of pyridine.…”