A Cobalt‐Catalyzed Multicomponent Approach to Novel 2,3‐Di‐ and 2,2,3‐Trisubstituted 3‐Methoxycarbonyl‐γ‐butyrolact­ones
A one-pot, three-component synthesis of the title butyrolactones starting from aryl bromides, dimethyl itaconate, and either aldehydes or ketones is described. The cobalt-catalyzed domino process formally involves the in situ metalation of an aromatic bromide, conjugate addition onto dimethyl itaconate, an aldolization reaction with a carbonyl compound and a final cyclization into a five-membered lactone. This procedure is applied to the concise synthesis of a range of functionalized γ-butyrolactones with a methyl paraconate subunit.