19596
In this Letter , we report the synthesis and biological evaluation of 2 ' - C - methyl - 6 - O - methyl - 7 - deaza guanosine and ProTide derivatives .
 2 ' - C - methyl - 6 - O - methyl -, guanosine
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
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Answer:
 2 ' - C - methyl - 6 - O - methyl -, guanosine