Targeted Discovery of a Natural ortho -Quinone Methide Precursor and Green Generation of Its Oligomers.

ortho -Quinone methides ( o -QMs) are a class of highly reactive intermediates that serve as important nonisolable building blocks (NBBs) in organic synthesis and small-molecule library construction. Because of their instability and nonisolability, most reported o -QMs are generated through in situ chemical synthesis, and only a few natural o -QMs have been reported due to the lack of directed discovery strategies. Herein, a new natural o -QM precursor (trichophenol A, 2 ) was identified from the fungal strain of Trichoderma sp. AT0167 through genome mining, which was generated by trilA (nonreducing polyketide synthase) and trilB (2-oxoglutarate dependent dioxygenase). Combinatorial biosynthesis via two other known NRPKS genes with trilA and trilB was performed, leading to the generation of five new trichophenol o -QM oligomers (trichophenols D-H, 5 - 9 ). The strategy combining genome mining with combinatorial biosynthesis not only targetedly uncovered a new natural o -QM precursor but also produced various new molecules through oligomerization of the new o -QM and its designated o -QM acceptors without chemical synthesis and isolation of intermediates, which was named NBB genome mining-combinatorial biosynthesis strategy for o -QM molecule library construction. This study provides a new strategy for the targeted discovery of natural o -QMs and small-molecule library construction with natural o -QMs.