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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.

Reactions of sulfur ylides with ketones and aldehydes to form epoxides are by far the most common application of the Johnson Corey Chaykovsky reaction . Examples involving complex substrates and ' exotic ' ylides have been reported , as shown below . The reaction has been used in a number of notable total syntheses including the Danishefsky Taxol total synthesis , which produces the chemotherapeutic drug taxol , and the Kuehne Strychnine total synthesis which produces the pesticide strychnine . fill in the blank : Reactions of sulfur ylides with ketones and aldehydes to __________________ epoxides are by far the most common application of the Johnson Corey Chaykovsky reaction .
Output:
form