Dehydrocollatolic Acid, a New Depsidone from the Lichen Parmotrema nilgherrense

Abstract

No abstract available.

Total Synthesis of the Resorcyclic Acid Lactone Spiroketal Citreoviranol

“…NaCl, dried over Na 2 SO 4 and concentrated in vacuo. Purification by flash column chromatography on silica (20:1 hexanes−Et 2 O) afforded 13a (757 mg, 54%) and 13b (526 mg, 38%) as pale yellow oils: 13a: 3,128.4,127.9,127.7,70.8,70.3,63.3,42.8,24.0,21.3,15.1;HRMS (ESI+) 1H,3.68 (ddt,J = 6.8,5.7,5.6 Hz,1H,, 3.59−3.54 (m, 2H, OCH 2 CH 3 ), 2.51 (dd, J = 5.4, 2.7 Hz, 2H, H-3), 2.03−1.96 (m, 1H, H-5 a ), 2.01 (t, J = 2.7 Hz, 1H, H-1), 1.79−1.72 (m, 1H, H-5 b ), 1.19 (t, J = 7.1 Hz, 3H, OCH 2 CH 3 ), 1.16 (d, J = 6.2 Hz, 3H, H-7); 13 C NMR (100 MHz, CDCl 3 ) δ 138. 3,128.3,127.8,127.6,93.3,80.9,74.2,71.1,70.2,70.2,63.3,41.2,23.7,20.3,15.1;HRMS (ESI+) for C 17 H 24 NaO 3 [M + Na] + requires 299.1618, found 299.1624.…”

“…This substructure has only been found in one other natural product, dehydrocollatolic acid (5) (Figure 1). 3 While RALs have been shown to have potential therapeutic value, neither citreoviranol (1) nor dehydrocollatolic acid (5) has been tested for biological activity. In addition, there have been no previous syntheses of the 6,6-spiroketal lactone ring system rendering these natural products attractive synthetic targets.…”

Evaluation of DNA polymerase inhibitory activities of depsidones, depsides and diaryl ethers from the Vietnamese lichen Rimelia clavulifera

“…The extracts were separated by column chromatography and preparative TLC to yield fourteen known compounds (figure 1). The known compounds were identified as dehydrocollatolic acid (1), [8] α-alectoronic acid (2), [9] α-collatolic acid (3), [10] β-alectoronic acid (4), [11] βcollatolic acid (5), [10] atranorin (6), [12] chloroatranorin (7), [13] gyrophoric acid (8), [14] salazinic acid (9), [15] lecanoric acid (10), [12] methyl orsellinate, methyl βorsellinate, (+)-usnic acid, and skyrin [16] by comparison of their spectroscopic data with those of literatures. Although these compounds are common lichen substances from the family of Parmeliaceae, this is the first report of the constituents of R. clavulifera.…”

Total Synthesis of Virgatolide B via Exploitation of Intramolecular Hydrogen Bonding

“…Virgatolides A-C (1−3, Figure 1) are a family of [6,6]benzannulated spiroketals, isolated in 2011 by Che et al during an investigation into fungal metabolites produced by the genus Pestalotiopsis. 1 During preliminary biological screening, an ethyl acetate extract of a fermentation culture of P. virgatula (L147) exhibited cytotoxicity toward HeLa (cervical epithelium) cells.…”

“…H NMR (400 MHz, CDCl 3 ) δ 7.36−7.31 (5H, m, Ar-H),6.68 (1H, d, J = 2.0 Hz, Ar-H), 6.49 (1H, d, J = 2.0 Hz, Ar-H), 5.15 (1H, d, J = 3.7 Hz, CH), 5.09 (2H, s, CH 2 ), 4.25−4.18 (1H, m, CH), 3.87 (3H, s, CH 3 ), 0.96 (3H, d, J = 6.6 Hz, CH 3 ), 0.82 (9H, s, CH 3 ), 0.04 (3H, s, CH 3 ), −0.02 (3H, s, CH 3 );13 C NMR (100 MHz, CDCl 3 ) δ 168.2 (CO), 165.3 (C), 159.4 (C), 152.2 (C), 135.7 (C), 128.7 (Ar-CH × 2), 128.3 (Ar-CH), 127.4 (Ar-CH × 2), 108.0 (C), 99.9 (Ar-CH), 99.5 (Ar-CH), 81.6 (CH), 70.4 (CH 2 ), 68.2 (CH), 55.8 (CH 3 ), 25.5 (CH 3 × 3), 17.8 (C), 17.6 (CH 3 ), −4.6 (CH 3 ), −5.1 (CH 3 ); IR (film) ν max 2953, 2929, 2856, 1755, 1602, 1471, 1322, 1210, 1154, 1021, 957, 833, 732 cm −1 ; HRMS (ESI+) calcd for C 24 H 32 O 5 Si [M + Na] + 451.1911, found 451.1897.3-(1-(Ethoxymethoxy)ethyl)-5-hydroxy-7-methoxyisobenzofuran-1(3H)-one (14). To a stirred solution of 5-(benzyloxy)-3-(1-(ethoxymethoxy)ethyl)-7-methoxyisobenzofuran-1(3H)-one (12; 110 mg, 0.29 mmol) in MeOH (6 mL) was added Pd/C (11 mg, 10% w/ w), and the mixture was stirred under H 2 at room temperature for 24 h. The reaction mixture was filtered through Celite and concentrated in vacuo.…”