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The synthesis of 22 structurally diverse urea , thiourea and acylthiourea derivatives containing the ( R ) - 2 - amino - 1 - butanol motif has been performed .
 Chemical: urea; Chemical: thiourea; Chemical: acylthiourea; Chemical: ( R ) - 2 - amino - 1 - butanol
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: urea; Chemical: thiourea; Chemical: acylthiourea; Chemical: ( R ) - 2 - amino - 1 - butanol