Conjugate Addition/[3,3] Sigmatropic Shift Processes for Formation of Medium-Ring Cyclic Amines - Do They Circumvent the Woodward-Hoffmann Rules?

Abstract

Herein we describe our exploration, using density functional theory calculations, of a conjugate addition-rearrangement sequence that leads to medium-ring cyclic amines. On the basis of the results of our calculations, we conclude that the rearrangement step is rate determining. In addition, we analyze the role of a carbanion lone pair in the rearrangement step, concluding that it functions as a substituent on a [3,3] sigmatropic shift, rather than a nucleophile; thus, the Woodward-Hoffmann rules are not circumvented in this reaction via involvement of orthogonal orbitals on an atom involved in the rearrangement.