- Efficient, scalable and economical preparation of tris(deuterium)- and 13C-labelled N-methyl-N-nitroso-p-toluenesulfonamide (Diazald) and their conversion to labelled diazomethane
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A method for the preparation of multi-gramme quantities of N-methyl-d3-N-nitroso-p-toluenesulfonamide (Diazald-d3) and N-methyl-13C-N-nitroso-p-toluenesulfonamide (Diazald-13C) and their conversion to diazomethane-d2 and diazomethane-13C, respectively, is presented. This approach uses robust and reliable chemistry, and critically, employs readily commercially available and inexpensivemethanol as the label source. Several reactions of labelled diazomethane are also reported, including alkene cyclopropanation, phenolmethylation and α-diazoketone formation, as well as deuteriumscrambling in the preparation of diazomethane-d2 and subsequent methyl esterification of benzoic acid.
- Shields, Samuel W.J.,Manthorpe, Jeffrey M.
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p. 674 - 679
(2015/01/16)
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- One-pot two-step enzymatic coupling of pyrimidine bases to 2-deoxy-D-ribose-5-phosphate. A new strategy in the synthesis of stable isotope labeled deoxynucleosides
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The enzymatic synthesis of thymidine from 2-deoxy-D-ribose-5-phosphate is achieved, in a one-pot two-step reaction using phosphoribomutase (PRM) and commercially available thymidine phosphorylase (TP). In the first step the sugar-5-phosphate is enzymatically rearranged to α-2-deoxy-D-ribose-1-phosphate. Highly active PRM is easily obtained from genetically modified overproducing E. coli cells (12000 units/84 mg protein) and is used without further purification. In the second step thymine is coupled to the sugar-1-phosphate. The thermodynamically unfavorable equilibrium is shifted to the product by addition of MnCl2 to precipitate inorganic phosphate. In this way the overall yield of the β-anomeric pure nucleoside increases from 14 to 60%. In contrast to uracil, cytosine is not accepted by TP as a substrate. Therefore, 2′-deoxy-cytidine is obtained by functional group transformations of the enzymatically prepared 2′-deoxy-uridine. The method has been demonstrated by the synthesis of [2′,5′-13C2]- and [1′,2′,5′-13C3]thymidine as well as [1′,2′,5′-13C3]2′-deoxyuridine and [3′,4′-13C2]2′-deoxycytidine. In addition the nucleoside bases thymine and uracil are tetralabeled at the (1,3-15N2,2,4-13C2)-atomic positions. All compounds are prepared without any scrambling or dilution of the labeled material and are thus obtained with a very high isotope enrichment (96-99%). In combination with the methods that have been developed earlier it is concluded that each of the 13C- and 15N-positions and combination of positions of the pyrimidine deoxynucleosides can be efficiently labeled starting from commercially available and highly 13C- or 15N-enriched formaldehyde, acetaldehyde, acetic acid, potassium cyanide, methylamine hydrochloride, and ammonia.
- Ouwerkerk,Steenweg,De Ruijter,Brouwer,Van Boom,Lugtenburg,Raap
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p. 1480 - 1489
(2007/10/03)
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