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 [ 13 C 1 ]-adenine to [ 13 C 3 ]-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 [1Ј,2Ј,5Ј,2-13 C 4 ]-2Ј-deoxy-D-

One- or Two-Step Synthesis of C-8 and N-9 Substituted Purines

“…Hermann Emil Fischer achieved the first synthesis of imidazo­[4,5- d ]­pyrimidine in 1898 . Since then, several synthetic routes to purine derivatives have been reported in literature. − For instance, 1,3,8-trisubstituted xanthines and 2,8-disubstituted adenines are obtained through cyclization of pyrimidine derivatives . Another illustration includes reactions such as SNAr-type substitutions or coupling reactions , on appropriately activated purines providing access to polyfunctionalized purines at positions 2, 6, 8, or 9.…”

“…1 H NMR (CDCl 3 , 300 MHz) δ 7.33−7.31 (m, 3H), 7.04−7.01 (m, 2H), 3.97 (t, 2H, J = 6.4 Hz), 3.15 (s, 2H), 2.96 (t, 2H, J = 6.4 Hz), 2.42 (t, 2H, J = 7.8 Hz), 1.74−1.64 (m, 2H), 1.40 (sex, 2H, J = 7.5 Hz), 0.94 (t, 3H, J = 7.5 Hz). 13 5-Amino-1-phenylethyl-2-propyl-1H-imidazole-4-carbonitrile (5). The crude residue was purified by silica gel chromatography eluting with 50% cyclohexane in ethyl acetate.…”

Discovery of novel dual inhibitors of receptor tyrosine kinases EGFR and PDGFR-β related to anticancer drug resistance

“…Commercial reagents were used without further purification. The 4-chloro pyrimidine 1b was prepared according to literature starting from the prepared 6-amino-2-mercatopyrimidine-4-ol given by the reaction of cyano acetic acid methyl ester and thiourea in sodium methanolate, a following thioether hydrolysis using raney nickel and a final 4-chlorination reaction using phosphorus oxychloride in DMF 18 . The 1 H-NMR spectra (400 MHz) were measured using tetramethylsilane as internal standard.…”

Isotope Labels Combined with Solution NMR Spectroscopy Make Visible the Invisible Conformations of Small-to-Large RNAs

“…In the final step, reaction with methanolic NH 3 in a microwave reactor yields the desired [2- 13 C]-adenine 29 (Scheme ). Alternative purine synthesis pathways have been devised to enable specific labeling of adenine C2 or any purine nitrogen position. ,,,− We recently synthesized [7- 15 N]-labeled 29 through intermediates 21 – 23 and 15 N-labeled intermediates 24 – 28 using the Battaglia-Ouwerkerk approach , and demonstrated its utility in NMR analysis of RNA structure and dynamics (Scheme ). …”

“…98 A preferred alternative for purine C2 labeling uses the method of Battaglia and Ouwerkerk and co-workers, wherein sodium ethoxide (C 2 H 5 ONa) mediates cyclization of ethyl cyanoacetate 21 with 13 C-thiourea 22 to give [2- 13 C]-6-amino-2-thiouracil 23. 99,100 Unlabeled sodium nitrite (NaNO 2 ) is then used for nitrosylation (the 15 N-labeled form can also be used to introduce a second isotope label) to form 24. Then sodium dithionite (Na 2 S 2 O 4 ) mediates the reduction of the nitroso group to yield 25 followed by desulfurization over Raney-Nickel to form the diaminopyrimidine 26.…”