Photocycloaddition with Ir catalysts in low volume reaction vessels. Blue light mediated [2+2] cycloaddition at 40 °C under magnetic stirring (1300 rpm).
0.8 mmol N-(tert-Butyl)-N-cinnamylacrylamide and 8.0 μmol [Ir(dtbbpy)[dF(CF₃)ppy]₂]PF₆ in 20 ml DMSO will react for 3-4 h with blue light. Purification by extraction with tert-butylmethylether and by silica gel column chromatography.