21425
Cross - coupling of alkyl halides with alkenes leading to Heck - type and addition products is summarized .
 Chemical: alkyl halides; Chemical: alkenes
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: alkyl halides; Chemical: alkenes