- Synthesis of Rovafovir Etalafenamide (Part IV): Evolution of the Synthetic Process to the Fluorinated Nucleoside Fragment
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Fluorinated nucleoside 1 is a key starting material in the synthesis of rovafovir etalafenamide (2), a novel nucleotide reverse transcriptase inhibitor under development at Gilead Sciences for the treatment of HIV. While an initial manufacturing route enabled the production of 1 to support clinical development, alternative approaches were explored to further enhance manufacturing effectiveness, improve processing time, reduce cost, and minimize the environmental impact. Toward this end, two new routes were developed to a key synthetic intermediate, which was converted to 1 using a new protecting group strategy. The new chemistry led to improvements in the manufacturing process while reducing the overall process mass intensity (PMI).
- Siler, David A.,Calimsiz, Selcuk,Doxsee, Ian J.,Kwong, Bernard,Ng, Jeffrey D.,Sarma, Keshab,Shen, Jinyu,Curl, Jonah W.,Davy, Jason A.,Garber, Jeffrey A. O.,Ha, Sura,Lapina, Olga,Lee, Jisung,Lin, Lennie,Park, Sangsun,Rosario, Mary,St-Jean, Olivier,Yu, Guojun
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p. 1263 - 1274
(2021/05/29)
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- Partial Protection of Carbohydrate Derivatives. Part 4. Regioselective 2'-O-Deacylation of Fully Acylated Purine and Pyrimidine Ribonucleosides with Hydroxylaminium Acetate
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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.
- Ishido, Yoshiharu,Sakairi, Nobuo,Okazaki, Kei,Nakazaki, Nobuo
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p. 563 - 573
(2007/10/02)
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