20210
The structure of compound 1 was elucidated on the basis of spectroscopic analysis , including HR - ESI - MS , 1D and 2D NMR spectra , and the absolute configurations of C - 2 and C - 3 for compound 1 were assigned by circular dichroism spectrometry combined with quantum chemical calculations .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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