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Information × Registration Number 0221U101691, 0120U100153 , R & D reports Title Development of new ways of obtaining substituted benzothiazoles, benzoxazoles, oxazolopyridines, thiazolopyridines, imidazopyrimidines and modification of their structures by transformation of functional groups popup.stage_title Head Tolkunov Sergej V., Доктор хімічних наук Registration Date 24-01-2021 Organization L.M. Litvinenko Institute of Physical-Organic Chemistry and Coal Chemistry of the NAS of Ukraine popup.description2  A general approach to the synthesis of oxazolo [4,5-b] pyridines and isoxazolo [5,4-b] pyridines based on acid-catalyzed heterocyclization of aminoisoxazole derivatives and heterocyclizations of methyl oxazolopyridine-6-carboxylates has been proposed. The synthetic limits of these reactions depending on the reagents, the reaction conditions, which allows a wide range of substituents. A convenient method for producing methyl oxazolo[4,5-b]pyridine-6-carboxylates by heterocyclization of methyl 2-amino-3-oxypyridine-5-carboxylates with orthoesters, bromocyanic and formic acid has been developed. It was found that the hydrolysis of methyl 2-R-oxazolo[4,5-b]pyridine-6-carboxylates is accompanied by the destruction of the oxazole cycle, leading to pyridine derivatives. The cyclocondensation of substituted 5-aminoisoxazoles with diethyl 2-oxosuccinate in trifluoroacetic acid was studied. It is shown that the condensation proceeds with the formation of two isomeric esters: diethyl (2E) -2- (5-amino-3-methylisoxazol-4-yl) -but-2-endioate and diethyl (2Z) -2- (5-amino- 3-methylisoxazol-4-yl) -but-2-endioate. The ability of the (2E) -isomer to give a cyclic derivative of ethyl 6-hydroxy-3-methyl- [1,2] oxazolo [5,4-b] pyridine-4-carboxylate has been established. It is shown that the heterocyclization of methyl 2-amino-3-oxypyridine-5-carboxylate by orthoesters, bromocyanine, formic acid is a convenient way to new methyl derivatives of 2-R-oxazolo [4,5-b] pyridine-6-carboxylates. Product Description popup.authors Bogza Sergey L. Smirnova Olga V. Tolkunov Andrey S. Tolkunov Valeriy S. Tolkunov Sergey V. Khyzhan Oleksandr I. popup.nrat_date 2021-01-24 Close