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

• Bilge Banu Yagci,
• Selin Ezgi Donmez,
• Onur Şahin and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2023, 19, 66–77, doi:10.3762/bjoc.19.6

• on the success of the catalytic aza-Nazarov reaction. Keywords: α-methylene-γ-lactam; aza-Nazarov reaction; β-silicon effect; heterocycles; intramolecular cyclization; Introduction The rapid construction of aliphatic heterocycles from acyclic building blocks via cyclization or cycloaddition

• N-acyliminium ion 28, the aza-Nazarov cyclization of which would provide the final product 30 through the intermediacy of 29 (Scheme 6). According to our hypothesis, the carbocation of intermediate 29 would be stabilized by the β-silicon effect similar to intermediate 9 (vide supra). Unfortunately

• the β-silicon effect in this aza-Nazarov cyclization. During the course of our studies, we observed occasionally the formation of aldehyde-containing side products, the amount of which increased when the aza-Nazarov cyclizations did not proceed efficiently. We proposed that, if the aza-Nazarov