Organocatalytic Reductive Amination of the Chiral Formylcyclopropanes: Scope and Applications
Akram Hussain,
Swamy Peraka,
Dhevalapally B. Ramachary
Abstract:We developed a sustainable three-component reductive amination protocol for the chemoselective coupling of optically active functionally rich donor− acceptor carbonyl-cyclopropanes with various amines under 10 mol % of diphenyl phosphate in the presence of Hantzsch ester as a hydride source. The catalytic selective reductive C−N coupling has wide advantages like no epimerization, no ring opening, large substrate scope, generating only mono N-alkylation products and simultaneously resulting in chiral cyclopropa… Show more
“…Hence, our investigation of the three-component Ramachary reductive C -alkylation commenced, 15 after synthesizing a library of C -7 alkylated products 3 from the commercially available triacetate lactone 1 with various aliphatic alkyl iodides or bromides 2 as starting materials using modified Hsung's protocol in very good to excellent yields (Scheme 2). 16 First, C -7 alkylation was performed by addition of n BuLi at −78 °C to 1 in THF and HMPA (6 : 1) followed by addition of ethyl iodide 2a , and stirring at 25 °C for 15 h gave the desired selective C -7 alkylated pyrone 3a in a very good yield of 85% (Scheme 2).…”
A simple two-step dialkylation protocol was developed to synthesize antibiotics photopyrones, pseudopyronines, and violapyrones from triacetate lactone in excellent yields.
“…Hence, our investigation of the three-component Ramachary reductive C -alkylation commenced, 15 after synthesizing a library of C -7 alkylated products 3 from the commercially available triacetate lactone 1 with various aliphatic alkyl iodides or bromides 2 as starting materials using modified Hsung's protocol in very good to excellent yields (Scheme 2). 16 First, C -7 alkylation was performed by addition of n BuLi at −78 °C to 1 in THF and HMPA (6 : 1) followed by addition of ethyl iodide 2a , and stirring at 25 °C for 15 h gave the desired selective C -7 alkylated pyrone 3a in a very good yield of 85% (Scheme 2).…”
A simple two-step dialkylation protocol was developed to synthesize antibiotics photopyrones, pseudopyronines, and violapyrones from triacetate lactone in excellent yields.
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