Ketenimines as Aza-Dienophiles
Christopher J. DeAngelis, G. Goyal, Marshall J. Liss, Jessica E. Budwitz, Mary Stuart Herlihy, Audrey V. Conner, Steven E. Wheeler, Pengchen Ma, M Li, K. N. Houk, Christopher G. Newton
Abstract
High Resolution Image Download MS PowerPoint Slide N -Aryl ketenimines have been established as highly reactive aza-dienophiles. Intermolecular cycloadditions are achieved upon heating in the presence of 2,5-bis(silyloxy)furans and proceed with high levels of peri-, regio-, chemo- and diastereo-selectivity. Spontaneous C–O cleavage yields oxygenated pyridone derivatives in a highly convergent and redox-neutral manner. Combined experimental and computational studies demonstrate N -aryl ketenimines to be significantly more reactive than imino dienophiles, as a consequence of less distorted transition states. Derivatization studies include the development of isocyanate and cyclic ketenimine equivalents as aza-dienophiles, while extension to a one-pot aza-Diels–Alder/oxa-Diels–Alder sequence provides a three-component approach to complex fused pyridone/pyran systems.