Solid-state double [2+2] photocycloaddition reactions of di-2-pyrones ……

Solid-state double [2+2] photocycloaddition reactions between di-2-pyrones (1a-d) with benzophenone (2a) afforded highly site- and regioselective oxetane derivatives (3a-d; 1:2 adducts) across the C5-C6 and C5′-C6′ double bonds in 1 via the triplet excited state of 2a. The structures of products were identified by 1H NMR、IR、MS and elemental analysis The solid-state photoreactions has several advantages such as mild reaction conditions, simple operation, environmental friendliness and good yield. The oxetane formation proceeded more effectively in the solid state than in solution. http://www.sjfcd.org/paperInfo.aspx?ID=896