Photochemistry of N-(pyrimidin-2-one-4-yl)pyridinium derivatives. The ring contraction of pyrimidinone into imidazolinone

Abstract

Abstract:Photochemical reactions (A > 300 nm) of N-(1-methylpyrimidin-2-one)-and N-(1,Sdimethylpyrimidin-2-0ne)pyridinium chlorides were studied in deoxygenated aqueous solution at various pH's. Only the former compound was found to be reactive under these conditions to give pyrimidine ring contraction photoproducts 1-methyl-4-imidazolin-2-one and 1 -methyl-4-imidazolin-2-one-5-carboxyaldehyde, with pH-dependent chemical yields. The photochemical pyrimidine ring contraction reaction does not occur for other photochemically reactive pyrimidin-2-ones bearing 3-methylimidazolium-l , 1,2,4-triazol-1 -y I, or imidazol-1-yl as substituents at the C-4 position. The suggested mechanism of the reaction involves the addition of water to the pyrimidinone part of the N-(1-methylpyrimidin-2-one)pyridinium salt in the excited triplet state as the primary photochemical step. Addition of alcohol to the pyridinium ring was found to be the major reaction under irradiation of N-(1-methylpyrimidin-2-one-4-y1)pyridinium chloride in methanol.Key words: photochemistry, N-(pyrimidin-2-one-4-y1)pyridinium compounds, pyrimidine ring contraction, 1-substituted-4-imidazolin-2-ones, 4-imidazolin-2-one-5-carboxyaldehydes.RCsumC : Operant j. divers pH, dans des solutions dCsoxygCnCes, on a CtudiC les reactions photochimiques (A > 300 nm) des chlorures de N-(1-mkthylpyrimidin-2-one)-et de N-(l,5-dimethylpyrimidin-2-one)pyridinium. On a trouve que, dans ces conditions, le premier compose est le seul h fournir des photoproduits resultant d'une contraction du noyau pyrimidine, soit la 1 -methyl-4-imidazolin-2-one et le 1-methyl-4-imidazolin-2-one 5-carboxyaldChyde avec des rendements qui varient avec le pH. La reaction photochimique de contraction du noyau pyrimidine ne se produit pas avec les autres pyrimidin-2-ones photochimiquement reactives portant des substituants 3-mCthylimidazolium-l,l,2,4-triazol-1 -yle ou imidazol-1-yle en position C-4. Le mecanisme suggCrC pour la rkaction implique que, dans l'etape photochimique primaire, il y a addition d'eau j. la portion pyrimidinone du sel N-(1-methylpyrimidin-2-0ne)pyridinium dans 1'Ctat excite triplet. Lors de l'irradiation du chlorure de N-(1-mkthylpyrimidin-2-one-4-y1)pyridinium dans le methanol, on observe que l'addition d'alcool est la reaction principale.Mots elks : photochimie, composes N-(pyrimidin-2-one-4-yl)pyridinium, contraction du noyau pyrimidine, 4-imidazolin-2-ones substituCes en position 1,4-imidazolin-2-one-5-carboxaldehydes.[Traduit par la redaction) Common purine and pyrimidine nucleosides such as guanosine, inosine, thymidine, and uridine can be easily and efficiently converted to the corresponding, fluorescent N-(purin-6-y1)-and N-(pyrimidin-2-one-4-y1)pyridinium chlorides (1). Some of these derivatives can be incorporated into synthetic

Methods for the synthesis of 1-substituted 1H-imidazol-2(3H)-ones

“…23,115,116 Irradiation with a high-pressure mercury lamp caused the rearrangement of 2,3,4-triphenylisoxazole-5(2H)-imine (86) to 1,4,5-triphenylimidazol-2(3Н)-one (1b) and 3-[(α-phenylamino)benzylidene]indolin-2-one (87) with 61% combined yield 23 (Scheme 93). The reaction was performed in EtOH or C 6 H 6 .…”

“…Photochemical reactions of 1-(1-R 3 -2-oxo-1,2-dihydropyrimidin-4-yl)pyridinium chlorides 88a,b were also studied in deoxygenated aqueous solutions at various pH values 115 the same conditions gave 1-substituted 1H-imidazol-2(3H)-ones 1bl,bm and 3-substituted 2-oxo-2,3-dihydro-1H-imidazole-4-carbaldehydes 1bn,bo, the yield of which depended on the reaction mixture pH (Table 7). Irradiation in aqueous solution at рН 6.5 gave aldehydes 1bn,bo as the major products, while mostly compounds 1bl,bm were formed in acidic medium (Table 7, lines 1, 5), and the yields of compounds 1bn,bo increased in alkaline medium ( Table 7, lines 2-4, 6).…”