RESUMEN
The truxillates constitute a large class of dimeric natural products featuring a central, highly substituted cyclobutane core. In principle, these structures could be efficiently synthesized via [2 + 2] photocycloaddition. However, the difficulty in controlling the high-energy electronically excited reactive intermediates in the solution state can lead to poor regio- and diastereocontrol. This has limited the use of photocycloaddition methodology toward the synthesis of this important class of natural products. Herein, we demonstrate that acid-controlled precipitation of C-acyl imidazoles promotes a highly selective solid-state photocycloaddition, and the products of this reaction can be quickly transformed into truxillate natural products.
RESUMEN
Herein, we describe studies showing that Lewis acid co-catalysts can significantly broaden the scope of alkenes that can be incorporated into the photosensitized visible-light De Mayo reaction. Mechanistic studies suggest that the primary benefit of the Lewis acid is not on substrate sensitization but rather on bond-forming steps downstream of energy transfer, highlighting the diverse effects that Lewis acids can have on sensitized photoreactions.