Notes- The Nature of the Alkyl Groups in Nidulin

Depsidone Derivatives and a Cyclopeptide Produced by Marine Fungus Aspergillus unguis under Chemical Induction and by Its Plasma Induced Mutant

“…The HMBC correlations from H-5′ to C-7 and from H-10′ to C-6′, C-7′ and C-8′, together with the 1 H– 1 H COSY correlations from H-8′ to H-9′, established a moiety of 1-methyl-1-propenyl and attached it to C-6′ of ring C. Finally, the two rings were connected by the HMBC correlation from H-11′ to C-7( 5 J CH ) to determine its structure ( Figure 2 ). As for the configuration of the 2-but-2-enyl group, it has been observed by Beach and Richards that O -methylisonidulin ( trans -configuration) has a higher splitting constant than nidulin ( cis -configuration) for the interaction between the two vinyl methyls across the double bond [ 18 ]. Compound 1 possesses a splitting constant of 0.8 Hz close to nidulin with a splitting constant of 1.0 Hz, indicating that the 2-but-2-enyl group in 1 is assigned to be cis -configuration.…”

Long-range splitting in the nuclear magnetic resonance spectrum of 1,4-dihydrobenzoic acid

“…Intense irradiation of the green solution with visible light, in dry, nonpolar solvents, produces a red, metastable form (dashed line in Figure 1) which returns very rapidly to the original green. 3 The orange, nonphotochromic dithizonate anion produced in alkaline solution is shown by the dotted line in Figure 1.…”