51549-20-3Relevant academic research and scientific papers
High-throughput five minute microwave accelerated glycosylation approach to the synthesis of nucleoside libraries
Bookser, Brett C.,Raffaele, Nicholas B.
, p. 173 - 179 (2007/10/03)
The Vorbrueggen glycosylation reaction was adapted into a one-step 5 min/130 °C microwave assisted reaction. Triethanolamine in acetontrile containing 2% water was determined to be optimal for the neutralization of trimethylsilyl inflate allowing for direct MPLC purification of the reaction mixture. When coupled with a NH3/methanol deprotection reaction, a high-throughput method of nucleoside library synthesis was enabled. The method was demonstrated by examining the ribosylation of 48 nitrogen containing heteroaromatic bases that included 25 purines, four pyrazolopyrimidines, two 8-azapurines, one 2-azapurine, two imidazopyridines, two benzimidazoles, three imidazoles, three 1,2,4-triazoles, two pyrimidines, two 3-deazapyrimidines, one quinazolinedione, and one alloxazine. Of these, 32 yielded single regioisomer products, and six resulted in separable mixtures. Seven examples provided inseparable regioisomer mixtures of -two to three compounds (16 nucleosides), and three examples failed to yield isolable products. For the 45 single isomers isolated, the average two-step overall yield ± SD was 26 ± 16%, and the average purity ± SD was 95 ± 6%. A total of 58 different nucleosides were prepared of which 15 had not previously been accessed directly from glycosylation/deprotection of a readily available base.
Partial Protection of Carbohydrate Derivatives. Part 4. Regioselective 2'-O-Deacylation of Fully Acylated Purine and Pyrimidine Ribonucleosides with Hydroxylaminium Acetate
Ishido, Yoshiharu,Sakairi, Nobuo,Okazaki, Kei,Nakazaki, Nobuo
, p. 563 - 573 (2007/10/02)
Like hydrazine hydrate, hydroxylamine was found to be useful for the regioselective 2'-O-deacylation of fully acylated purine and pyrimidine ribonucleosides as its salt with acetic acid; the partial O-deacylation reactions (which were not accompanied by undesirable discolouration as happens with hydrazine hydrate) gave the corresponding di-O-acylribonucleosides in superior yields; e.g. 2',3'-di-O-benzoyladenosine (74percent yield), 3',5'- (64percent yield) and 2',5'-di-O-benzoyl-N6-benzyladenosine (63percent yield on performing the reaction in ethanol), N2,3',5'-tri-O-benzoylguanosine (66percent yield), N2,2',5'-tri-isobutyrylguanosine (48percent yield), and 3',5'-di-O-benzoyluridine (61percent yield) were obtained using hydroxylaminium acetate in pyridine.Treatment of fully acetylated ribonucleosides with an excess of hydroxylaminium acetate gave the corresponding 5'-O-acetylribonucleosides in quantitative yields.The excellent regioselectivity observed in the present partial O-decyclation was confirmed on the basis of chromatographic separation; the mixtures of di-O-acylribonucleosides, which had already been equilibrated in pyridine, were re-equilibrated on the silica gel during separation, e.g. a 70 : 30 mixture of 3',5'- and 2',5'-di-O-benzoyladenosine was completely converted into the former based on 1H n.m.r spectroscopy.The acetates of 9-β-D-xylo- and -arabino-furanosyladenine were also found to give predominantly the corresponding 3',5'-diacetates on hydroxylaminolysis.
