N6-Ethenopurines as Fluorophores

N6-Ethenoderivatives of adenosine (2 -deoxy adenosine) may be obtained as metabolites from the reaction of DNA with vinyl chloride, chloroacetaldehyde or chloroethylenoxide [321]. Excitation wavelength of such heterocycles is 300 nm with a maximum of emission at 412 nm. Phosphoramidite (131) and similar compounds have been incorporated into oligonucleotides [322-324], 

Crosslinking of DNA and proteins is a versatile method to study protein-DNA interactions. Among others, phosphoramidites of brominated or iodinated 2 -deoxycytidines [325], 2 -desoxuridines [326,327] and recently also of 2 -deoxyadenosines 132 have been used [328]. Nucleophilic replacement of the bromine by an amino group during deprotection does not occur when reaction conditions of concentrated ammonia solution for 24 h at room temperature are used after oligonucleotide synthesis. 

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