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The key step was the elimination of HBr in a vicinal dibromo D - homosteroid by treatment with 1 , 4 - diazabicyclo [ 2 . 2 . 2 ] octane ( DABCO ) .
 Chemical: HBr; Chemical: vicinal dibromo D - homosteroid; Chemical: 1 , 4 - diazabicyclo [ 2 . 2 . 2 ] octane; Chemical: DABCO
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: HBr; Chemical: vicinal dibromo D - homosteroid; Chemical: 1 , 4 - diazabicyclo [ 2 . 2 . 2 ] octane; Chemical: DABCO