Template-Directed Selective Photodimerization Reactions of 5-Arylpenta-2,4-dienoic Acids.

We developed an efficient method that enables selective photodimerization of 5-arylpenta-2,4-dienoic acids (i.e., vinylogous cinnamic acids).

Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles.

We have developed a catalytic aza-Nazarov reaction of -acyliminium salts generated in situ from the reaction of a variety of cyclic and acyclic imines with α,β-unsaturated acyl chlorides to afford substituted α-methylene-γ-lactam heterocycles. The reactions proceed effectively in the presence of catalytic (20 mol %) amounts of AgOTf as an anion exchange agent or hydrogen-bond donors such as squaramides and thioureas as anion-binding organocatalysts. The aza-Nazarov cyclization of 3,4-dihydroisoquinolines with α,β-unsaturated acyl chlorides gives tricyclic lactam products in up to 79% yield with full diastereocontrol (dr = >99:1).

Template-Directed Photochemical Homodimerization and Heterodimerization Reactions of Cinnamic Acids.

We developed a general method for the selective photochemical homo- and heterodimerization of cinnamic acid derivatives with the use of commercially available 1,8-dihydroxynaphthalene as a covalent template. A variety of symmetrical and unsymmetrical β-truxinic acids were obtained in high yields and as single diastereomers. The use of a template not only provides the alignment of the two olefins with suitable proximity (<4.