Oxidation Of Adenosine And Inosine: The Chemistry Of 8-oxo-7,8-dihydropurines, Purine Iminoquinones, And Purine Quinones As Observed By Ultrafast Spectroscopy

Oxidative damage to purine nucleic acid bases proceeds through quinoidal intermediates derived from their corresponding 8-oxo-7,8-dihydropurine bases. Oxidation studies of 8-oxo-7,8-dihyroadenosine and 8-oxo-7,8-dihydroinosine indicate that these quinoidal species can produce stable cross links with a wide variety of nucleophiles in the 2-positions of the purines. An azide precursor for the adenosine iminoquinone has been synthesized and applied in ultrafast transient absorption spectroscopic studies. Thus, the adenosine iminoquinone can be observed directly, and its susceptibility to nudeophilic attack with various nucleophiles as well as the stability of the resulting cross linked species have been evaluated Finally, these observations indicate that this azide might be a very useful photoaffurity labeling agent, because the reactive intermediate, adenosine iminoquinone, is such a good mimic for the universal purine base adenosine

Photoaffinity Labeling Strategies Using Purine Nucleic Acid Bases

Photodecomposition of 8-azidoadenosine and 8-azidoinosine has been studied by ultrafast transient absorption spectroscopy methods in different solvents, including water solutions with different pH values. The formation of two types of intermediates has been proposed their photodecomposition: diiminoquinone with an EDG on the purine ring, and iminonitriles in the absence of an EDG on the purine ring. Iminoquinone and iminonitrlies undergoes nucleophilic attack forming C2-adducts. Imidazole adduct, water adduct, reduction product, and ring destruction products has been isolated. Small amounts of dimer-like structures and other products have been detected, but have not been fully identified. Synthesis of 6-azido-8-oxopurinoriboside has been performed for the first time. Photodecomposition of this azide has been studied by ultrafast transient absorption spectroscopy methods. The formation of iminoquinone as reactive intermediate has been proposed for photodecomposition of this azide in protic solvents. This iminoquinone leads to the formation of C2- and C6-adducts, and the reduction product. Imidazole adduct, 8-oxoadenosine , and 8-oxoinosine have been isolated and characterized from the reparative irradiation of 6-azido-8-oxopurinoriboside. Small amounts of other photodecomposition products have been detected, but have not been fully identified

Photoaffinity Labeling Strategies Using Purine Nucleic Acid Bases

Photodecomposition of 8-azidoadenosine and 8-azidoinosine has been studied by ultrafast transient absorption spectroscopy methods in different solvents, including water solutions with different pH values. The formation of two types of intermediates has been proposed their photodecomposition: diiminoquinone with an EDG on the purine ring, and iminonitriles in the absence of an EDG on the purine ring. Iminoquinone and iminonitrlies undergoes nucleophilic attack forming C2-adducts. Imidazole adduct, water adduct, reduction product, and ring destruction products has been isolated. Small amounts of dimer-like structures and other products have been detected, but have not been fully identified. Synthesis of 6-azido-8-oxopurinoriboside has been performed for the first time. Photodecomposition of this azide has been studied by ultrafast transient absorption spectroscopy methods. The formation of iminoquinone as reactive intermediate has been proposed for photodecomposition of this azide in protic solvents. This iminoquinone leads to the formation of C2- and C6-adducts, and the reduction product. Imidazole adduct, 8-oxoadenosine , and 8-oxoinosine have been isolated and characterized from the reparative irradiation of 6-azido-8-oxopurinoriboside. Small amounts of other photodecomposition products have been detected, but have not been fully identified

Reactions of N,3-diarylpropiolamides with arenes under superelectrophilic activation: synthesis of 4,4-diaryl-3,4-dihydroquinolin-2(1H)-ones and their derivatives

The reaction of 3-aryl-N-(aryl)propiolamides with arenes in TfOH at room temperature for 0.5 h led to 4,4-diaryl-3,4-dihydroquinolin-2-(1H)-ones in yields of 44–98%. The obtained dihydroquinolinones were further transformed into the corresponding N-acyl or N-formyl derivatives. For the latter, the superelectrophilic activation of the N-formyl group by TfOH in the reaction with benzene resulted in the formation of N-(diphenylmethyl)-substituted dihydroquinolinones