A carbenoid is a reactive chemical species that resembles a carbene, which is a molecule containing a carbon atom with only two bonds instead of the usual four. Carbenoids are often used in organic chemistry as intermediates in various reactions, particularly in the formation of new carbon-carbon bonds. They can be generated from certain precursors, such as metal complexes or halogenated compounds, and are valuable for synthesizing complex organic molecules. One common type of carbenoid is the Simmons-Smith reagent, which is used to convert alkenes into cyclopropanes. Carbenoids can also participate in insertion reactions and rearrangements, making them versatile tools in synthetic chemistry. Their unique properties allow chemists to explore new pathways for creating diverse chemical structures.