Substituent Effects on Competitive Release of Phenols and 1,3-Rearrangement in α-Keto Amide Photochemistry

<UFIGR ID="ol036459qn00001">Photolysis of α-keto amides bearing 4-YC<INF>6</INF>H<INF>4</INF>O leaving groups at the position α to the keto group efficiently produces high yields of phenols when Y is an electron-withdrawing group or H. The photoelimination likely involves cleavage of zwitterionic intermediates produced via excited-state hydrogen transfer. When Y is an electron-donating group, competing excited-state ArO−C<INF>α</INF> bond scission to radicals occurs, followed by recombination to give 1,3-photorearrangment products.