Pure intermediate
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United States of America Patent
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Oct 6, 2015
Grant Date -
Aug 8, 2013
app pub date -
Aug 26, 2011
filing date -
Aug 27, 2010
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Abstract
The present invention relates to an improved process for the preparation of Letrozole (I) and its synthetic intermediate 4-[(1-(1,2,4-triazoly)methyl]benzonitrile (III). In particular, it relates to a process to prepare Letrozole and its intermediate (III) substantially free from regioisomeric impurities. The present invention further relates to acid addition salts of 4-[(1-(1,2,4-triazoly)methyl]benzonitrile (III) such as the oxalate salt, and also to Letrozole (I), the intermediate (III) and salts thereof preparable by the processes of the present invention.
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