Stereodynamic tetrahydrobiisoindole “NU-BIPHEP(O)”s: functionalization, rotational barriers and non-covalent interactions

• Golo Storch,
• Sebastian Pallmann,
• Frank Rominger and
• Oliver Trapp

Beilstein J. Org. Chem. 2016, 12, 1453–1458, doi:10.3762/bjoc.12.141

• phase design. The “NU-BIPHEP(O)” 3 was isolated in 49% yield and again three isomeric species were observed by NMR spectroscopy in CDCl3 due to hindered rotation of the tertiary amide bond (Figure 2A). Intriguingly, only two peaks were observed upon investigation of 3 by enantioselective HPLC applying n

Synthesis and determination of the absolute configuration of (−)-(5R,6Z)-dendrolasin-5-acetate from the nudibranch Hypselodoris jacksoni

• I. Wayan Mudianta,
• Victoria L. Challinor,
• Anne E. Winters,
• Karen L. Cheney,
• James J. De Voss and
• Mary J. Garson

Beilstein J. Org. Chem. 2013, 9, 2925–2933, doi:10.3762/bjoc.9.329

• obtained by preparative enantioselective HPLC. Keywords: enantioselective HPLC; E/Z-isomers; Hypselodoris; natural products; nudibranch; sesquiterpene; Introduction Marine organisms have been proven a prolific source of natural products that potentially can be used as lead compounds or which have

• , although such data must be interpreted with care. With the individual characterization of the E/Z-isomers accomplished, preparative enantioselective HPLC separation of racemic (Z)-5-hydroxydendrolasin (7b) was next undertaken (Figure 4) and provided samples of both of the (+)-7b and (−)-7b isomers

• . Enantioselective HPLC analyses run under identical conditions using 5% isopropanol in n-hexane were carried out on the synthetic sample of racemic 1, the two synthetically prepared R and S enantiomers of 1, and the natural sample as shown in Figure 7. The data revealed a clear separation of the individual

Mutational analysis of a phenazine biosynthetic gene cluster in Streptomyces anulatus 9663

• Orwah Saleh,
• Katrin Flinspach,
• Lucia Westrich,
• Andreas Kulik,
• Bertolt Gust,
• Hans-Peter Fiedler and
• Lutz Heide

Beilstein J. Org. Chem. 2012, 8, 501–513, doi:10.3762/bjoc.8.57

• summarized in Table 2, and the 1H-1H COSY, HSQC and HMBC correlations are depicted in Figure S2 (Supporting Information File 1). The configuration at the α-carbon of the amino acid was determined as L-Gln by enantioselective HPLC analysis [16] (see Experimental section). The specific rotation was determined

• stereochemical configuration of endophenazine E The configuration of the amino acid glutamine in the structure of PCA-Gln was determined as described by Lämmerhofer and Lindner [16], by using an enantioselective HPLC system with two complementary chiral columns, which contained either quinine (QN) or quinidine