title: Metal-free, mild, nonepimerizing, chemo- and enantio- or diastereoselective N-alkylation of amines by alcohols via oxidation/imine-iminium formation/reductive amination: a pragmatic synthesis of octahydropyrazinopyridoindoles and higher ring analogues.
abstract: A mild step and atom-economical nonepimerizing chemo- and enantioselective N-alkylating procedure has been developed via oxidation/imine-iminium formation/reduction cascade using TEMPO-BAIB-HEH-Brønsted acid catalysis in DMPU as solvent and a stoichiometric amount of amine. The optimized conditions were further extended for the nonenzymatic kinetic resolution of the chiral amine thus formed under nonenzymatic in situ hydrogen-transfer conditions using VAPOL-derived phosphoric acid (VAPOL-PA) as the Brønsted acid catalyst. The enantioselective cascade of the presented reaction was successfully utilized in the synthesis of octahydropyrazinopyridoindole and its higher ring analogues.
authors.affiliation: Laboratory No. 101, Medicinal and Process Chemistry Division (MPC), CSIR-Central Drug Research Institute (CDRI) , Chattar Manzil Palace, Lucknow, Uttar Pradesh 226-001, India.
authors.forename: Imran A
authors.initials: IA
authors.lastname: Khan
authors.forename: Anil K
authors.initials: AK
authors.lastname: Saxena
mesh_terms: D000438:Alcohols / Q000737:chemistry*; D000478:Alkylation; D000586:Amination; D000588:Amines / Q000737:chemistry*; D007097:Imines / Q000138:chemical synthesis* / Q000737:chemistry; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011719:Pyrazines / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000438:Alcohols; D000588:Amines; D007097:Imines; D007211:Indoles; D011719:Pyrazines; D011725:Pyridines