Synthesis of α-ketols by functionalization of captodative alkenes and divergent preparation of heterocycles and natural products

Captodative alkene 1-acetylvinyl p-nitrobenzenecarboxylate 1a was evaluated for its reactivity in Lewis acid-catalyzed Michael additions with functionalized benzene rings and heterocycles, leading to diverse conjugated addition adducts. The hydrolysis of the latter resulted in the desired functionalized α-ketols, including natural alkaloid actinopolymorphol B (24a). The α-ketol core structure of these compounds was used as the building block for the synthesis of the natural alkaloid tanakine (25) and for the divergent construction of highly substituted heterocycles, such as 4-oxazolin-2-ones and butenolides, and their respective fused polycyclic derivatives.