LAUSR

In this account, we have summarized the recent developments in Hauser-Kraus (H-K) annulation with respect to the synthesis of natural products, other functionalized and fused carbocycles and spiro-heterocycles. Although classical H-K annulation is between a 1,4-dipolar synthon (a 3-nucleophilic phthalide), and a 1,2-dipolar synthon (a Michael acceptor), alternative modes of annulation such as [4+4] and [4+1] as well as other reactivity of 3-nucleophilic phthalide which were reported in recent years are also covered in this account.