Detailed Instructions: In this task, you will be given a passage to read. A fill in the blank question will be given to you. Your answer should fit the blank appropriately.
Q: In addition to the reactions originally reported by Johnson , Corey , and Chaykovsky , sulfur ylides have been used for a number of related homologation reactions that tend to be grouped under the same name . With epoxides and aziridines the reaction serves as a ring @-@ expansion to produce the corresponding oxetane or azetidine . The long reaction times required for these reactions prevent them from occurring as significant side reactions when synthesizing epoxides and aziridines . Several cycloadditions wherein the ylide serves as a nucleophilic carbenoid equivalent have been reported . Living polymerizations using trialkylboranes as the catalyst and ( dimethyloxosulfaniumyl ) methanide as the monomer have been reported for the synthesis of various complex polymers . fill in the blank : __________________ addition to the reactions orig__________________ally reported by Johnson , Corey , and Chaykovsky , sulfur ylides have been used for a number of related homologation reactions that tend to be grouped under the same name .
A:
In