What is "cyclopropanation"

n. (context organic chemistry English) Any reaction that introduces a cyclopropane ring into a compound

Cyclopropanation refers to any chemical process which generates cyclopropane rings. It is an important process in modern chemistry as many useful compounds bear this motif; for example pyrethroids and a number of quinolone based antibiotics ( Ciprofloxacin, Sparfloxacin, etc.). However the high ring strain present in cyclopropanes makes them challenging to produce and generally requires the use of highly reactive species, such as carbenes, ylids and carbanions. Many of the reactions proceed in a cheletropic manner.