21598
The sterically hindered Z - stereoisomer 1 , a new natural product , was prepared by time - dependent photoisomerization of the E - isomer ( 2 ) under UV irradiation at lambda 254 nm , while 2 , 3 , 5 , 7 - tetramethoxyphenanthrene ( 5 ) was identified at lambda 365 nm by UHPLC / APCI - MS and NMR spectroscopy .
 Chemical: 2 , 3 , 5 , 7 - tetramethoxyphenanthrene
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: 2 , 3 , 5 , 7 - tetramethoxyphenanthrene