Mild and efficient synthesis and base-promoted rearrangement of novel isoxazolo[4,5-b]pyridines

• Vladislav V. Nikol’skiy,
• Mikhail E. Minyaev,
• Maxim A. Bastrakov and
• Alexey M. Starosotnikov

Beilstein J. Org. Chem. 2024, 20, 1069–1075, doi:10.3762/bjoc.20.94

• the basis of readily available 2-chloro-3-nitropyridines via the intramolecular nucleophilic substitution of the nitro group as a key step. The previously unknown base-promoted Boulton–Katritzky rearrangement of isoxazolo[4,5-b]pyridine-3-carbaldehyde arylhydrazones into 3-hydroxy-2-(2-aryl[1,2,3

• general synthetic scheme (Scheme 1C), commercially available 2-chloro-3-nitropyridines 1a–c were reacted with ethyl acetoacetate in the presence of NaH to give compounds 2a–c which were not isolated and directly subjected to an in situ nitrosation affording isonitroso compounds 3a–c in good yields

• , for example a formyl group. Thus, the key isonitroso compounds 7 were synthesized from chlorides 1a–c via in situ formation of pyridylacetoacetic esters 2a–c followed by decarbonylation to give 2-methyl-3-nitropyridines 5a–c [24] which were used in the next step without purification. Their reactions

Nucleophilic dearomatization of 4-aza-6-nitrobenzofuroxan by CH acids in the synthesis of pharmacology-oriented compounds

• Alexey M. Starosotnikov,
• Dmitry V. Shkaev,
• Maxim A. Bastrakov,
• Ivan V. Fedyanin,
• Svyatoslav A. Shevelev and
• Igor L. Dalinger

Beilstein J. Org. Chem. 2017, 13, 2854–2861, doi:10.3762/bjoc.13.277

• the design of pharmacology-oriented heterocyclic systems. Keywords: CH acids; dearomatization; 1,4-dihydropyridines; furoxans; nitropyridines; Introduction The reactions of condensed furoxans with CH acidic compounds have been extensively studied. There are two main possibilities for these reactions