This modification requires aryl or vinyl Grignards. Adding just the Grignard and the alkene does not result in a reaction demonstrating that the presence of oxygen is essential.

What do Grignard reagents react with?

Grignard reagents are formed by the reaction of magnesium metal with alkyl or alkenyl halides. They're extremely good nucleophiles, reacting with electrophiles such as carbonyl compounds (aldehydes, ketones, esters, carbon dioxide, etc) and epoxides.

Do Grignard reagents react with alkanes?

Grignard reagents react with water to produce alkanes. This is the reason that everything has to be very dry during the preparation above. For example: The inorganic product, Mg(OH)Br, is referred to as a "basic bromide".