Synthesis of [1′,2′,5′,2-13C4]-2′-Deoxy-D-adenosine by a Chemoenzymatic Strategy to Enable Labelling of Any of the 215 Carbon-13 and Nitrogen-15 Isotopomers

Abstract

Enzymatic trans-N-glycosylation has been selected as the method of choice by which to couple [13C1]-adenine to [13C3]-2-deoxy-D-ribose. The enzymatic pentosylation of the labelled adenine base was achieved in a two-step/one-pot reaction, starting from thymidine labelled in the sugar ring, but not at the thymine base. The efficiency of this thymidine phosphorylase catalysed (TP-catalysed) and purine nucleoside phosphorylase catalysed (PNP-catalysed) transamination reaction was demonstrated by a high yield (91%) and stereochemical purity of the obtained [1′,2′,5′,2-13C4]-2′-deoxy-D-adenosine. To verify that all carbon and nitrogen positions and combination of positions in both the adenine and the sugar could be substituted by 13C and 15N at a minimum of cost, each of the steps was optimised to convert the commercially available and isotopically highly enriched (99%) synthons (acetaldehyde, acetic acid, ammonia, benzylamine, formic acid, methylamine, potassium cyanide, potassium thiocyanate and sodium nitrite) as quantitatively as possible. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)