Synthesis of Tetrahydroazepines through Silyl Aza-Prins Cyclization Mediated by Iron(III) Salts

Abstract

A new methodology for the synthesis of seven-membered unsaturated azacycles (tetrahydroazepines) was developed. It is based on the powerful aza-Prins cyclization in combination with the Peterson-type elimination reaction. In a single reaction step, a C–N, C–C bond and an endocyclic double bond are formed. Under mild reaction conditions and using iron(III) salts as sustainable catalysts, tetrahydroazepines with different degrees of substitution are obtained directly and efficiently. DFT calculations supported the proposed mechanism.

Bicyclic N-dihalocyclopropylamide derivatives as precursors of nitrogen-containing fused polycyclic systems

“…This is consistent with the reputation of seven-membered rings to be comparatively challenging to make. 15…”

Recent Advances in Non-Precious Metal Catalysis

“…Padrón and colleagues developed a method to construct both six-membered and seven-membered N -heterocycles using iron catalysis (Scheme ). In the synthesis of piperidine, 2-substituted homoallyl sulfonyl amide was first prepared in a FeCl 3 -catalyzed one-pot reaction between a sulfonyl amide, an aldehyde, and allyltrimethylsilane in a complementary approach reported by Fan et al (Scheme a) .…”