title: Exploration of photochemical reactions of N-trimethylsilylmethyl-substituted uracil, pyridone, and pyrrolidone derivatives.
abstract: Photochemical reactions of N-trimethylsilylmethyl-substituted uracil, pyridone and pyrrolidone derivatives were carried out to determine if silicone containing substituents have an impact on excited state reaction profiles. The results show that ultraviolet irradiation of N-trimethylsilylmethyl substituted uracils in the presence of substituted alkenes leads to efficient formation of both dimeric and cross [2+2]-cycloaddition products. Qualitatively similar observations were made in a study of the photochemistry of N-trimethylsilylmethyl-2-pyridone. The combined results demonstrate that [2+2]-photocycloaddition is a more efficient excited state reaction pathway for the uracil and pyridone substrates as compared to other processes, such as ylide-forming trimethylsilyl group C-to-O migration. Finally, photoreactions of N-trimethylsilylmethyl-2-pyrrolidone in solutions containing dipolarophiles, such as methyl acrylate, lead to the formation of the desilylation product, N-methyl-2-pyrrolidone by way of a simple, non-ylide generating, protodesilylation process. In addition, observations were made which show that orbital symmetry allowed photocycloreversion reactions of dimeric uracil derivatives, involving cyclobutane ring splitting, to take place. These processes, which lead to the formation of monomeric uracils, appear to be stimulated by the presence of electron donor groups on the cyclobutane ring, a likely result of a new SET promoted cyclobutane ring cleavage pathway. In the cases of N-trimethylsilylmethyl-substituted cyclobutane derivatives that possess phthalimide groups, highly efficient excited state cleavage of the cyclobutane moiety occurs to produce uracil derivatives and corresponding vinyl phthalimide.
authors.affiliation: Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan, 609-735, Korea.
authors.forename: Dae Won
authors.initials: DW
authors.lastname: Cho
authors.forename: Chan Woo
authors.initials: CW
authors.lastname: Lee
authors.forename: Jong Gu
authors.initials: JG
authors.lastname: Park
authors.forename: Sun Wha
authors.initials: SW
authors.lastname: Oh
authors.forename: Nam Kyoung
authors.initials: NK
authors.lastname: Sung
authors.forename: Hea Jung
authors.initials: HJ
authors.lastname: Park
authors.forename: Kyung Mok
authors.initials: KM
authors.lastname: Kim
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Mariano
authors.forename: Ung Chan
authors.initials: UC
authors.lastname: Yoon
mesh_terms: D000179:Acrylates / Q000737:chemistry; D000475:Alkenes / Q000737:chemistry; D003500:Cyclization; D055668:Photochemical Processes; D011760:Pyrrolidinones / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry; D014297:Trimethylsilyl Compounds / Q000737:chemistry*; D014466:Ultraviolet Rays; D014498:Uracil / Q000031:analogs & derivatives*
chemical_list: D000179:Acrylates; D000475:Alkenes; D011760:Pyrrolidinones; D014297:Trimethylsilyl Compounds; D014498:Uracil; C028537:2-pyrrolidone; C035956:methyl acrylate; D012825:Silicon