Diäthyloxamidsäureester wurde mit Mesityloxyd resp. Cyclohexanon kondensiert und lieferte dabei ω, ω-Dimethyl-acryloyl-brenztraubensäure-diäthylamid (VII) resp. Cyclohexanon-(2′)-yl-(1′)-glyoxylsäure-diäthylamid (VIII). VII konnte nicht analog den ent-sprechenden Estern in das isomere Dihydro-γ-pyronderivat übergeführt werden.
Atropisomeric enone-imides and enone-amides featuring N-CAryl bond rotation were evaluated for intramolecular [2 + 2] photocycloaddition. Straight addition product was observed over cross-addition product with good control over reactivity. The atropselectivity was found to be dependent on the substituent on the aryl ring. Substitution-dependent atropselectivity was rationalized on the basis of a divergent