The Syntheses and Absolute Configurations of Fomannoxin, (−)-5-Acetyl-2-(1-Hydroxymethylvinyl)-2,3-Dihydrobenzofuran, and Anodendroic Acid

Abstract

The title compounds were synthesized from (−)-(S)- or (+)-(R)-2,3-dihydrobenzofuran-2-carboxylic acid. And their absolute configurations were determined.

Application of Phenolate Ion Mediated Intramolecular Epoxide Ring Opening in the Enantioselective Synthesis of Functionalized 2,3-Dihydrobenzofurans and 1-Benzopyrans¹

“…Purification of the crude product by silica gel column chromatography (4% EtOAc in n-hexane) afforded 27b (0.22 g, 75%) as a colorless oil; 27 [a] D 25 +10.6 (c 1.0, EtOH) {Lit. 31 The above physical and spectroscopic data were consistent with the literature data. 8…”

Prenylated Phenol and Benzofuran Derivatives from Aspergillus terreus EN-539, an Endophytic Fungus Derived from Marine Red Alga Laurencia okamurai

“…The measured ECD spectral behavior (Figure 3) of 5 assigned its absolute configuration as R unambiguously. The optical rotations of 4 and 5 were measured as [α]D25 = −95.0 ( c 0.29, MeOH) and [α]D25 = −55.0 ( c 0.51, MeOH), respectively, which satisfied the reported correspondances between sterechemistry and optical rotations ( R configuration with negative OR and S configuration with positive OR) for anodendroic acid [18], (+)- S -anodendroic acid [16], asperterreusine C [17], and ( S )-5-formyl-2-(isopropyl-1′-ol)-2,3-dihydrobenzofuran [21]. This corresponding relationship was further verified by OR calculation at the B3LYP/6-31G(d) level in Gaussian 09 [20].…”

“…However, the relationship between absolute configuration and optical rotation for the known compounds anodendroic acid ( 4 ) and asperterreusine C ( 5 ) was ambiguous in the literature, and their absolute configurations were therefore discussed and confirmed by TDDFT-ECD and OR calculations. Anodendroic acid ( 4 ) was first isolated from the higher plant Anodendron affine Durce with optical rotation of [α]D26 = −19 ( c 0.7, EtOH) [15], and then its absolute configuration was determined as being R by chemical synthesis, with optical rotation of [α]D15 = −35.2 ( c 0.682, EtOH) [18]. Recently, the (+)- S -anodendroic acid was isolated and identified from another higher plant Euodia lepta , with an optical rotation of [α]D25 = +42.0 ( c 0.15, EtOH) [16].…”

Isolation and Characterization of Two New Metabolites from the Sponge-Derived Fungus Aspergillus sp. LS34 by OSMAC Approach

“…The configuration of the double bond between C-6 and C-9 was assigned as E form according to a NOESY correlation between H-6 and H-10, as well as a large coupling constant of 15.7 Hz. The absolute configuration of the C-2 chiral center in 1 was determined to be R by comparing the optical rotation value ([α]normalD25 −4.0) with that of alcohol [(−)−V] previously reported in the literature [22]. Detailed data can be found in Figures S3–S9.…”