On the green catalytic synthesis of purpurogallin

Abstract

The catalytic oxidation under green conditions of pyrogallol into purpurogallin was performed by air with laccase model copper complexes or by plant extracts containing peroxidases in the presence of hydrogen peroxide. A study was conducted for turnip, depending on the amount of extract, the method of introduction and the pH. Optimization of these conditions made it possible to easily obtain pure purpurogallin with a yield of 78%.

Study of Diels–Alder Reactions of Purpurogallin Tetraacetate with Various Dienophiles

“…Purpurogallin (1) presents an intramolecular hydrogen bond which makes it difficult to modify the hydroxyl involved in this bond (see Figure 3). We have shown that purpurogallin (1) can be obtained by catalytic oxidation of pyrogallol according to our previous work [13]. Purpurogallin (1) presents an intramolecular hydrogen bond which makes it difficult to modify the hydroxyl involved in this bond (see Figure 3).…”

“…Purpurogallin ( 1) can yet be converted into purpurogallin tetraacetate by peracetylation with acetic anhydride in the presence of DMAP [14] as catalyst in a yield of 87% according to the Scheme 1). We have shown that purpurogallin (1) can be obtained by catalytic oxidation of pyrogallol according to our previous work [13]. Purpurogallin (1) presents an intramolecular hydrogen bond which makes it difficult to modify the hydroxyl involved in this bond (see Figure 3).…”

“…Many benzotropolones are known as secondary metabolites, such from the fungus Fomes fomentarius [10], goupiolone A, isolated from the Goupia glabra, a plant from the Amazon region of Peru [11], and crocipo extracted from the fungus Leccinum crocipodium (Boletales) [12], see Figur Many benzotropolones are known as secondary metabolites, such as fomentariol from the fungus Fomes fomentarius [10], goupiolone A, isolated from the aerial parts of Goupia glabra, a plant from the Amazon region of Peru [11], and crocipodin, a pigment extracted from the fungus Leccinum crocipodium (Boletales) [12], see Figure 2. We have shown that purpurogallin (1) can be obtained by catalytic oxidation of pyrogallol according to our previous work [13]. Purpurogallin (1) presents an intramolecular hydrogen bond which makes it difficult to modify the hydroxyl involved in this bond (see Figure 3).…”

“…Only significant absorptions are listed. 1 H NMR (400 MHz) and 13 C NMR (100 MHz) spectra were recorded while using CDCl 3 or DMSO-d6 with TMS as an internal standard on a Bruker DPX 400 NMR spectrometer. Chemical shifts are reported in ppm.…”

“…The reaction mixture is heated to 130 • C for 20 h. After cooling, the solvent is evaporated off, a solid is recovered which is purified by column chromatography with, as eluent, hexane/ethyl acetate (1:1 3 Hz, J = 4.0 Hz); 7.22 (2H, d, J = 4 Hz); 6.79 (1H, s); 6.68 (1H, d, J = 8.0 Hz); 6.06 (1H, dd, J = 8.0 Hz; J = 9.9 Hz); 4.72 (1H, dd, J = 9.9, J = 1.8 Hz); 4.39 (1H, d, J = 5.8 Hz); 3.64 (1H, dd, J = 5.8 Hz, J = 1.8 Hz); 2.32 (3H, s); 2.30 (6H, s); 2.24 (3H, s). 13…”