AlCl₃/PCC-SiO₂-Promoted Oxidation of Azaindoles and Indoles

Embedding electron-deficient nitrogen atoms in polymer backbone towards high performance n-type polymer field-effect transistors

“…Then, the alkylation of 3 gave the corresponding alkylated azaindole ( 4 ) in 82% yield, which was further oxidated through pyridinium chlorochromate (PCC) to afford 6-bromo-7-azaisatin in 68% yield. 13 Interestingly, 6,6′-dibromo-7,7′-azaisoindigo was also observed in 10% yield in this oxidation reaction. 13 a Further investigation revealed that 6,6′-dibromo-7,7′-azaisoindigo was afforded exclusively in 36% yield when using dry PCC and excess AlCl 3 .…”

Design, Synthesis, and Biological Evaluation of 4-Quinoline Carboxylic Acids as Inhibitors of Dihydroorotate Dehydrogenase

“…Initial attempts to generate this focused on oxidation of aza-indoles to yield the corresponding aza-isatin for subsequent Pfitzinger condensation. However, reactions involving PCC oxidation 35 or a reusable poly aniline catalyst 36 on 1,6-aza-indoles did not provide the desired 1,6aza-isatin. Inspired by the work of Stockmann et al 37 and Zong et al, 38 we sought to generate our naphthyridine series by installing an α-keto ester on an aminopyridine amide precursor, 38 which would provide an intermediate for a subsequent Pfitzinger condensation.…”

Ylide mediated carbonyl homologations for the preparation of isatin derivatives

“…Additionally, most of these methods do not allow for easy control of regiochemistry, limiting the substrate scope of the reaction. Recently, several improved protocols have been put forth including copper-catalyzed C-H oxidations, [27][28][29] selenium-mediated oxidations, 30 indole oxidations, 31 arynebased methods, 32 Sandmeyer modifications, 33 and molecular elaboration of simple isatin synthons. 34 Many of these methods, however, still display limited substrate scope or harsh reaction conditions.…”