ring formation reaction step Johnson-Corey-Chaykovsky reaction Corey-Chaykovsky reaction RXNO RXNO:0000598 Reaction of a sulfur ylide with a double-bond to produce a three-membered ring. https://www.rsc.org/Merck-Index/reaction/r88/ https://www.wikidata.org/wiki/Q1582682 Johnson-Corey-Chaykovsky epoxide synthesis Johnson-Corey-Chaykovsky cyclopropane synthesis Johnson-Corey-Chaykovsky aziridine synthesis Johnson-Corey-Chaykovsky thiirane synthesis