What is Kucherov reaction?
The Kucherov reaction, also referred to as the Kucherov coupling or Kucherov condensation, involves the hydration of acetylenic hydrocarbons in the presence of a catalyst, such as mercuric sulfate HgSO4 or boron trifluoride BF3, and dilute sulfuric acid H2SO4, yielding ketones.

The Kucherov reaction is not commonly referred to by its name and is considered a rare reaction. Mechanistically, the reaction serves as an example of the electrophilic addition to an alkyne.

In line with Markovnikov’s rule, the reaction involves the addition of hydrogen (H⊕ or any other electrophilic part of a molecule) to the least substituted carbon, or the carbon atom with fewer hydrogen atoms.
References
Kutscheroff, M. (1881), Ueber eine neue Methode direkter Addition von Wasser (Hydratation) an die Kohlenwasserstoffe der Acetylenreihe. [On a new method of direct addition of water (hydration) to hydrocarbons of the acetylene series.] Ber. Dtsch. Chem. Ges., 14: 1540-1542. https://doi.org/10.1002/cber.188101401320