The Photocyclization of N,N-Dialkyl β-Oxo Amides on Silica Gel

Abstract
β-Oxo amides 1 adsorbed on silica gel underwent photocyclization via δ-hydrogen abstraction to give the five-membered lactams 2. No severe restrictions on the molecular motion could be observed in the photoreaction on the silica-gel surface. However, the relative photoreactivity of N,N-dibenzyl-2-benzoylacetamide (1a) to N,N-dibenzyl-2-benzoylpropionamide (1b) increased greatly on the silica-gel surface compared to that in solution, probably because of the greater keto content on the surface.