Heterocyclic Ketene Aminals: Scaffolds for Heterocycle Molecular Diversity

Investigation on the interaction between a heterocyclic aminal derivative, SBDC, and human serum albumin.

Heterocyclic ketene aminals bearing a secondary amino moiety acted as hetero-ene components to react with a number of enones under very mild conditions. The reaction of five- and six-membered heterocyclic ketene aminals 5 and 8 with methyl vinyl ketone proceeded effectively through the aza-ene addition, imine–enamine tautomerization and intramolecular cyclization to give good yields of 8-aroyl-5-hydroxy-5-methyl-1,2,3,5,6,7-hexahydroimidazo[1,2-a]pyridines 6 and 9-aroyl-6-hydroxy-6-methyl-1,2,3,4,7,8-hexahydroxy-6H-pyrido[1,2-a]pyrimidines 9, respectively. When methyl vinyl ketone was present in excess, preliminarily formed product 6 underwent a second aza-ene reaction followed by intramolecular cyclization and water-participating debenzoylation, to yield the cisoid-4,9-dihydroxy-4,9-dimethyl-1,2,5,6,6a,7,8,10α-octahydro-4H,9H-imidazo[1,2,3-ij][1,8]naphthyridin-10α-ylium benzoate 7 as the sole product. In refluxing acetonitrile, heterocyclic ketene aminals 5 underwent aza-ene addition and cyclocondensation reaction with a number of substituted α,β-unsaturated ketones to afford 1,2,3,7-tetrahydroimidazo[1,2-a]pyridine derivatives 23 while tricyclic imidazo[1,2-a]quinoline derivatives were easily obtained when 2-benzylidene-cyclohexanone and -cyclohexane-1,3-dione were used as enophiles. The effect of the structures of heterocyclic ketene aminals, particularly of the intramolecular hydrogen bond, on the aza-ene reactivity is also discussed.

The aza-ene reaction of heterocyclic ketene aminals with enones: an efficient and simple synthetic route to fused di- and tri-heterocycles

Solvent-free, microwave assisted synthesis of polyhalo heterocyclic ketene aminals as novel anti-cancer agents.

The aza-ene reaction of heterocyclic kentene aminals with enones: An unusual and efficient formation of imidazo[1,2-a] pyridine and imidazo[1,2,3-ij][1,8]naphthyridine derivatives

Heterocyclic ketene aminals 1–3 react with benzyl chloride to give the benzyl-substituted compounds 4–6. With ethyl bromoacetate, 1–3 react smoothly, and γ-lactam-fused heterobicycles 9–11 are obtained by further cyclocondensation of the alkylation products.



Alkylierung von Heterocyclischen Keten-aminalen mit Benzylchlorid und Bromessigsaure-ethylester. Synthese von Heterobicyclen bestehend aus γ-Lactam-verknupften Diazaheterocyclen



Heterocyclische Keten-aminale 1–3 reagieren mit Benzylchlorid zu den Benzyl-substituierten Verbindungen 4–6. Bromessigsaure ethylester liefert analoge Alkylierungsprodukte, die zu den γ-Lactamen 9–11 cyclisieren.

Alkylation of Heterocyclic Ketene Aminals with Benzyl Chloride and Ethyl Bromoacetate. Synthesis of Heterobicycles Containing γ‐Lactam‐Fused Diazaheterocycles

Alkylation of Heterocyclic Ketene Aminals with Benzyl Chloride and Ethyl Bromoacetate. Synthesis of Heterobicycles Containing γ‐Lactam‐Fused Diazaheterocycles.

Zhi-Rong Liu

Papers

Alkylation of Heterocyclic Ketene Aminals with Benzyl Chloride and Ethyl Bromoacetate. Synthesis of Heterobicycles Containing γ‐Lactam‐Fused Diazaheterocycles

Alkylation of Heterocyclic Ketene Aminals with Benzyl Chloride and Ethyl Bromoacetate. Synthesis of Heterobicycles Containing γ‐Lactam‐Fused Diazaheterocycles.