Calcium peroxide diperoxohydrate as a storable chemical generator of singlet oxygen for organic synthesis

Calcium peroxide diperoxohydrate (CaO2.2H(2)O(2)) is an environmentally friendly generator of singlet oxygen (O-1(2), (1)Delta(g)) that can be used in organic synthesis as an alternative to the regular photochemical method. This compound produces O-1(2) in various solvents and can be easily recovered by filtration for further regeneration, Both monitoring of O-1(2) luminescence at 1270 nm and specific trapping have shown that CaO2.2H(2)O(2) can be stored for several days at -80 degreesC and that the yield of O-1(2) is equal to 25%. Oxidation of typical organic substrates in methanol or THF through [4 + 2] or [2 + 2] cycloaddition and ene reaction have been carried out on a preparative scale with total conversion and selectivity.