Synthesis of 3-Arylpropenyl, 3-Arylpropynyl and 3-Arylpropyl 2-Azetidinones as Cholesterol Absorption Inhibitors: Application of the Palladium-Catalyzed Arylation of Alkenes and Alkynes

A series of 3-(3′-arylpropenyl)-2-azetidinones 8a–8k and 3-(3′-arylpropynyl)-2-azetidinones 16m–16p were prepared by the palladium-catalyzed arylation of 3-(3′-propenyl)-2-azetidinone 7, or by arylation of 4-pentenoic acid, or via ethyl 4-pentynoate followed by 2-azetidinone ring construction. The unsaturated 2-azetidinones were transformed to their saturated analogs 9a–9p by catalytic hydrogenation. Azetidinones 8a–8k, 9a–9p, and 16m–16p were evaluated for their biological activity as cholesterol absorption inhibitors in hamsters.