1616399-25-7Relevant academic research and scientific papers
Lithiation of N,N,N′,N′-tetraisopropylpyridine-2,6- dicarboxamide: Synthesis, characterization and single crystal X-ray studies of chalcogen (Se/Te) derivatives of N,N,N′,N′-tetraisopropylpyridine-2, 6-dicarboxamide
Dhau, Jaspreet S.,Dhir, Rupy,Singh, Avtar,Singh, Amritpal,Brand?o, Paula,Félix, Vítor
, p. 4876 - 4883 (2014)
The lithiation of N,N,N′,N′-tetraisopropylpyridine-2,6- dicarboxamide (1) and its application in the synthesis of chalcogen (Se/Te) derivatives was investigated. It was found that the selectivity of the reaction changed with the change in the amount of n-BuLi used. The lithiation of 1 with 6.1 equiv of n-BuLi followed by subsequent reactions with selenium/tellurium and iodomethane exclusively afforded the monosubstituted chalcogen derivative (2a/2b) in excellent yield. However, the use of 2.1 or 4.2 equiv of n-BuLi gave two additional products along with 2a/2b. One of the isolated products corresponded to the double lithiation of 1 and the other to the ortho lithiation followed by nucleophilic addition of n-BuLi to the one of the two carbonyl moieties. The prepared compounds have been characterized by single crystal X-ray crystallography, NMR (1H, 13C, 77Se and 125Te), IR, UV-Visible and Mass spectroscopy. Crystal structure of N,N,N′,N′-tetraisopropyl-3,5-bis(methyltelluryl)pyridine-2, 6-dicarboxamide (3b) reveals a strong intramolecular ?O?Te secondary and intermolecular Te?π pyridyl interactions.
