Assignment of proton and carbon NMR signals of didemnin A in solution

Several one‐ and two‐dimensional techniques have been used to assign the ¹H and ¹³C NMR spectra of the cyclic heptadepsipeptide didemnin A in DMSO. The composition and sequence of the amino acid residues was known beforehand and could be confirmed by heteronuclear proton–carbon long‐range couplings using the COLOC experiment and a recently proposed new inverse technique using Gaussian‐shaped pulses. The aliphatic methyl resonances of the isostatin, hydroxyisovalerylpropionyl, N‐methylleucine and leucine residues were assigned by means of the TOCSY and NOESY techniques. Aliphatic carbon assignment was performed by inverse correlation via heteronuclear double quantum coherence.