19178
The structures of 1 - 4 were elucidated from spectroscopic data ( NMR , MS , and IR ) , and the absolute configuration of 1 was determined by X - ray diffraction analysis .
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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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