Conformationally restricted spin labelled nucleotides: a model study of the synthesis and properties of the 2′,3′-O-spiro ketal of uridine and 4-oxo-2,2,6,6-tetramethyl-1-piperidyloxy

Abstract

The synthesis of 2′,3′-O-(1-oxy-2,2,6,6-tetramethyl-4-piperidylidene)uridine 13 is described in a model study directed at the corresponding spin labelled spiro ketal derivative of ATP (adenosine triphosphate)1 and of other nucleotides. The synthesis proceeds via acid-catalysed addition of 5′-O-benzoyluridine to 1-acetoxy-4-methoxy-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridine 9. The spiro ketal 11 from this reaction exists as two slowly interconverting conformers at room temperature. Prolonged alkaline hydrolysis and concomitant aerial oxidation gives the required product 13.