Synthesis of Some Substituted 2H-Pyrano[3,2-c]pyridine-2,5(6H)-diones. Reaction of Their 3-Acetyl Derivatives with Methyl 3-Amino-2-butenoate

General Method for the Preparation of Substituted 2-Amino-4H,5H-pyrano[4,3-b]pyran-5-ones and 2-Amino-4H-pyrano[3,2-c]pyridine-5-ones

“…Many years thereafter, Shaker [3] re-ported several applications of this reaction where he also used 4-hydroxycoumarin and α,β-unsaturated nitriles in order to prepare A and some of its analogues without, however, referring to either of the preceding publications [1,2]. In the course of our recent studies on the synthesis and the antituberculosis activity of 2-imino-7-methyl-1,6(6H)-naphthyridine derivatives (C) [4] and of 2H-pyrano [3,2-c]pyridines (D) as their oxygen analogues [5], we needed to obtain some structurally similar representatives of the 2-amino-4H,5H-pyrano [4,3-b]pyrans and the 2-amino-4H-pyrano [3,2-c]pyridines. For that purpose we successfully extended the known reaction, discussed above, to a general method for their preparation.…”

Syntheses of 3-[(Alkylamino)methylene]-6-methylpyridine-2,4(1H,3H)-diones, 3-Substituted 7-Methyl-2H-pyrano[3,2-c]pyridine-2,5(6H)-dione Fluorescence Probes, and Tetrahydro-1H,9H-2,10-dioxa-9-azaanthracen-1-ones

“…Since the synthesis of a monocyclic pyridinone, 6-methyl-3-[(phenylamino)methylene]pyridine-2,4(1 H ,3 H )-dione ( 18 ), has been reported through the coupling reaction of 4-hydroxy-6-methylpyridin-2(1 H )-one ( 17 ), triethyl orthoformate, and aniline, 4 we treated compound 17 with primary amines such as benzylamine and adenine separately under similar reaction conditions, and found that monocyclic pyridinones 1 and 3 , respectively, formed in 68% and 50% yields (Scheme 1). In the case of adenine, the C6-primary amino function appears to react faster than the C9-secondary amino group.…”

“…Aldehyde 19 was prepared according to a previously established synthetic route starting from pyridinone 17 4 as described in Scheme 1.…”

“…The spectral data for aldehyde 19 are similar to those previously reported. 4 Various monocyclic pyridi- none enamines, 1 – 7 , were synthesized in good to excellent yields by treating aldehyde 19 with primary and secondary amines in ethanol (Scheme 1). Compounds 1 , 2 , and 4 – 7 could be obtained at room temperature by treating aldehyde 19 with benzylamine, 4-hydroxybenzylamine, piperidine, N -methylpiperazine, N -phenylpiperazine, and morpholine, respectively, however, condensation with adenine to form compound 3 required an elevated temperature to achieve product formation.…”

“…Aldehyde 19 proved to be a versatile scaffold 4 through which to construct various bicyclic pyridinone structures by treating it with various doubly activated esters such as methyl α-(phenylsulfinyl)acetate, methyl α-(phenylsulfonyl)acetate, ethyl 3-oxo-3-phenylpropanoate, γ-(Boc-amino)-β-keto ester 20 , 10 and β-keto ester 22 in refluxing ethanol, employing piperidine as the catalyst (Scheme 2). The mechanism by which compounds 8 – 12 are formed is expected to proceed via Knoevenagel condensation 4 of the ester with aldehyde 19 followed by intramolecular lac-tone formation.…”