Question

Why is epoxidation one of the most frequently used reactions in organic chemistry?

Answer 1

Well, you take an olefin, and make a three-membered ring...........

Explanation:

And from the three-membered epoxide ring, once ring-opened, you can get TWO functionalized sites.

And these days, epoxidation is not only highly chemically efficient and selective, it is increasingly highly stereochemically selective. Look up `"Sharpless peroxidation"`, which won for its inventor, Barry Sharpless, a Nobel prize in 2001.