71831-74-8Relevant academic research and scientific papers
Selective Functionalization of Aminoheterocycles by a Pyrylium Salt
Moser, Daniel,Duan, Yaya,Wang, Feng,Ma, Yuanhong,O'Neill, Matthew J.,Cornella, Josep
, p. 11035 - 11039 (2018/07/31)
The functionalization of aminoheterocycles by using a pyrylium tetrafluoroborate reagent (Pyry-BF4) is presented. This reagent efficiently condenses with a great variety of heterocyclic amines and primes the C?N bond for nucleophilic aromatic substitution. More than 60 examples for the formation of C?O, C?N, C?S, or C?SO2R bonds are disclosed herein. In contrast to C?N activation through diazotization and polyalkylation, this method is characterized by its mild conditions and impressive functional-group tolerance. In addition to small-molecule derivatization, Pyry-BF4 allows the introduction of functional groups in a late-stage fashion to furnish highly functionalized structures.
Synthetic Applications of N-N Linked Heterocycles. Part 12. The Preparation of 4-Alkylthio- and 4-Arylthio-pyridines by Regiospecific Attack of Thioalkoxide Ions on N-(4-Oxopyridin-1-yl)pyridinium Salts
Sammes, Michael P.,Leung, Christopher W. F.,Mak, Chi Keung,Katritzky, Alan R.
, p. 1585 - 1590 (2007/10/02)
Thiolate ions add regiospecifically to N-(4-oxopyridin-1-yl)pyridinium salts (2)-(7) to give in good to excellent yields only the 1,4-dihydropyridine adducts (8)-(13), regardless of whether or not the pyridone moiety carries substituents for sterically shielding the 2- and 6-positions of the pyridinium ring.The addition is believed to be thermodynamically controlled.Decomposition of the dihydro-adducts under free-radical conditions, or by pyrolysis, gives good yields of pyridin-4-yl thioethers (14) and (16) though the reaction failed with the 2-methyl adducts (9).An improved synthesis of 6-methyl-4-oxopyran-2-carboxylic acid is also described.
