First Total Synthesis of 9‐Hydroxy‐8H‐pyrano[3,2‐f]indol‐2‐one

Abstract

A simple and efficient approach to synthesize a novel pyrrolocoumarin 9-hydroxy-8H-pyrano[3,2-f]indol-2-one (7) has been described. Starting from vanillin, the key intermediate 7-methoxy-1H-indol-6-yl propiolate (6) was synthesized in six steps. Then, the target compound was obtained by forming pyrone-ring and demethylation simultaneously in one step. A plausible mechanism invoking PtCl 4 catalyzed one-step reaction of cyclization and demethylation was also presented.

Mechanochemical synthesis of coumarins via Pechmann condensation under solvent-free conditions: an easy access to coumarins and annulated pyrano[2,3-f] and [3,2-f]indoles

“…Linear pyranoindoles may be considered as aza-analogues of psoralene. 26 5-Hydroxy-and 6-hydroxyindoles were selected as starting phenolic compounds that are easily available via Nenitsesku 27 and modified Bischler-Möhlau reactions. 28 Scheme 2 Scope of substrates for coumarin synthesis via the Pechmann condensation.…”

Formal Total Syntheses of (+)- and (−)-Aspidophytine from a Common, Homochiral Precursor

“…Specifically, vanillin (27) was acetylated under standard conditions and so providing acetate 28 in 90% yield. Electrophilic nitration of the latter compound under standard conditions then afforded the previously reported 22 arene 29 which was subjected to ester cleavage using potassium carbonate in methanol. The ensuing phenol was immediately O-methylated under standard conditions and so providing the known 23 dimethoxylated benzaldehyde 30 (40% ex.…”

Annulated Heterocyclic[g]Coumarin Composites: Synthetic Approaches and Bioactive Profiling

“…In 2019, Lipeeva and his team [47] tried to create a new series of AHCCs by lengthening the triazole linker with an alkyne chain. Among these substances, compound (58) was created via a cycloaddition reaction involving 1,9-decadiyne (55) and intermediate (48), which is the typical starting point in their synthetic approaches. Subsequently, as Scheme 10 shows, the compound (56) reacted with the coumarin derivative (57) to produce the desired compound (58) via Sonogashira's reaction.…”

“…Subsequently, as Scheme 10 shows, the compound (56) reacted with the coumarin derivative (57) to produce the desired compound (58) via Sonogashira's reaction. Compound (58) was evaluated for its antibacterial efficacy against Bacillus subtilis and Escherichia coli, with streptomycin serving as a positive control. [48] With minimum inhibitory concentration (MIC) values of 0.15 and 0.02 μM/ml, respectively, compound (58) showed strong inhibitory action against these bacterial strains.…”

“…Compound (58) was evaluated for its antibacterial efficacy against Bacillus subtilis and Escherichia coli, with streptomycin serving as a positive control. [48] With minimum inhibitory concentration (MIC) values of 0.15 and 0.02 μM/ml, respectively, compound (58) showed strong inhibitory action against these bacterial strains. According to the results, compound (58) was approximately six times more potent against Escherichia coli and 100 times more potent against Bacillus subtilis when compared to streptomycin (MIC values were 1 and 2 μM/ml, respectively).…”