- Process for preparing entecavir and intermediates thereof
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It comprises the preparation of entecavir of formula (I), or a pharmaceutically acceptable salt thereof, or a hydrate thereof by submitting a compound of formula (III) where X is an halogen selected from Cl, Br, and I, first to a hydrolysis reaction using formic acid and then to a deprotection reaction, and isolating the entecavir either as free base or as a pharmaceutically acceptable salt. It also comprises intermediates which intervene in this preparation process.
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- Preparation process of an antiviral drug and intermediates thereof
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Preparation process of an antiviral drug and intermediates thereof It comprises a preparation process of entecavir comprising: submitting a (1S,3R)-3-(tert-butyldimethylsilyloxy)-1-(oxiran-2-yl)pent-4-yn-1-ol (VIII) to a double esterification and to a radicalary cyclization, yielding a compound of formula (V), where either a compound of formula (VIII) is submitted to a first esterification reaction, then to a catalytic radicalary cyclization using titanocene dichloride as catalyst in the presence of Mn/2,4,6-collidine HCl or Zn/2,4,6-collidine/trimethylsilyl chloride, and finally to a second esterification reaction or, alternatively, the compound of formula (VIII) is submitted first to a catalytic radicalary cyclization, and then to an esterification reaction. Entecavir can be obtained by submitting compound (V) to a desilylation reaction to remove the TBS group and then to a Mitsunobu coupling with 2-amino-6-chloroguanine, followed by hydrolysis. It also relates to some new intermediates of the process.
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