1912
In comparison to conventional methods , experimental simplicity , good functional group tolerance , excellent yields , short routine , and selectivity without the need for a transition metal or base catalyst are prominent features of this green procedure .
 Chemical: transition metal
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: transition metal