Figure 1.
Key 2D NMR spectroscopic correlations establishing the connectivity of callophycolide A. a) 1H-1H COSY (bold), HMBC (red single-headed arrows), and HSQC-TOCSY (blue double-headed arrow) correlations; b) ROESY (red double-headed arrows) correlations establishing configurations for macrocyclic olefins in 1.