Photocyclo addition of acetone to uracil and cytosine.
D000096:Acetone; D003503:Cyclobutanes; D003596:Cytosine / Q000528:radiation effects*; D004988:Ethers, Cyclic; D010777:Photochemistry; D011830:Radiation Effects; D014466:Ultraviolet Rays; D014498:Uracil / Q000528:radiation effects*
D003503:Cyclobutanes; D004988:Ethers, Cyclic; D000096:Acetone; D014498:Uracil; D003596:Cytosine