Isonitrile-containing natural products isolated from bacteria, fungi, sponges, and plants have attracted wide attention in medicinal chemistry attributed to their fascinating chemical properties and potent bioactivities [1]. The isonitrile functional group may act as a nucleophile, an electrophile, or a carbene, and thus can participate in multiple types of reactions including the Ugi reaction and click chemistry [1, 2, 3, 4, 5]. In addition to this intrinsic reactivity, the isonitrile group displays a strong metal chelating feature that is often related to the biological activities of the isonitrile natural products [1]. Specifically, the isonitrile lipopeptides (INLPs) discovered from pathogenic Mycobacterium tuberculosis were suggested to mediate metal transport and be associated with M. tuberculosis virulence [∗6, 7, 8]. So far, more than 200 isonitrile-containing alkaloids, terpenes, epoxy compounds, and lipopeptides have been isolated from nature and many of them exhibit antibacterial, antifungal, antimalarial, antiviral, or anticancer activities [1,9, 10, 11, 12, 13].

In comparison to a long history of isonitrile natural product discovery and characterization, the biosynthesis of isonitrile natural products was relatively underexplored. Until now, two types of biosynthetic mechanisms for isonitrile have been reported: one through “isonitrile synthases” and the other through non-heme iron (II) and α-ketoglutarate (KG) dependent dioxygenases [14]. Isonitrile synthases such as IsnA and XanB are mainly involved in the biosynthesis of indole or tyrosine derived vinyl isocyanides and have been discussed in a few reviews recently [2,14, 15, 16]. Here, we aim to provide a brief review on the INLP biosynthetic pathways that utilize the non-heme iron (II) and α-KG dependent dioxygenases for isonitrile biogenesis.