Synthesis of methyl 4-aryl-6-methyl-4,7-dihydro-1H-pyrazolo-[3,4-b]pyridine-5-carboxylates from methyl 4-aryl-6-methyl-2-oxo-1,2,3,4-tetrahydropyridine-5-carboxylates

Synthesis and structural analysis of 5‐cyanodihydropyrazolo[3,4‐b]pyridines

“…Similar ring conformations for the orientation of the phenyl group at C-4 to that previously reported [18] was found.…”

“…The tautomerism analysis by solution NMR, crystallographic and theoretical studies showed the 2H-tautomer as the predominant form both in solution and in solid states. The presence of the phenyl ring at C-3 and its possible delocalization with pyrazole ring seems to be the main reason for why the 2H tautomers are preferred in compounds 4 over that of 1H tautomers (found in [18] as the preferred). The finding that the 1H tautomer as the preferred in compound 6d, where the phenyl is farther from the plane that those found for 4 also supports the theory that the phenyl ring at C3 influences the stability of the 2H tautomer through delocalization with the pyrazole ring.…”

1H and 13C spectral assignment of o‐chloroformyl substituted 1,4‐dihydropyridine derivatives

“…5,6 In spite of the widely developed chemistry of the 1,4-DHPs, the presence of substituents other than hydrogen atoms or alkyl groups on C-2 and C-6 of the 1,4-DHP ring has been less studied. 7 We have recently proved that these compounds are excellent intermediates in the synthesis of other heterocyclic fused 1,4-DHPs, such as pyrazolo [3,4-b]pyridines 8 and thieno [2,3-b]pyridines. 9 In this work we report the 1 H and 13 C NMR assignments of a series of differently substituted o-chloroformyl 1,4-DHP derivatives (1a-1; see Fig.…”

Synthesis of 3-Unsubstituted 4-Aryl-4,7-Dihydrothieno[2,3-b]Pyridine-2,5-Dicarboxylates / 3-Neaizvietotu 4-Aril-4,7-Dihidrotiēno[2,3-B]Piridīn-2,5-Dikarbonskābes Esteru Sintēze

“…According to literature data [32], enolic form of pyridone 5 is involved in the reaction with in situ generated Wilsmeier-Haack reagent. The following basic hydrolysis of formed intermediate, iminium salt, gave products 6.…”