Crystal structure and the degradation products of Tenvermectin B

The purpose of this work was to investigate the crystal structure and degradant products (DPs) of tenvermectin B (TVM B). A suitable crystal of TVM B was obtained from a solvent system (MeOH:formamide:H₂O = 2:5:2) and its absolute configuration was unambiguously established by single-crystal X-ray diffraction analysis. Meanwhile, a formamide-assisted crystallisation method for the purification of TVM B was developed. During the stress degradation studies of TVM B, four DPs (DPs 1-4) were prepared and characterised by MS and NMR. Among them, DP 2 and DP 3 have not been reported previously. In addition, the nematocidal activity of these DPs were evaluated.