Donor/donor carbenes are relatively new in the field of carbene chemistry; although applications in C−H and X−H insertion reactions are few in number, they demonstrate exquisite chemo‐ and stereo‐selectivity. Recent reports have shown that C−H, N−H, B−H, O−H, S−H, Si−H, Ge−H, Sn−H and P−H insertion reactions are feasible with a variety of transition metal catalysts, both inter‐ and intramolecularly. Furthermore, high degrees of diastereo‐ and enantioselectivity have been observed in several cases. Methods typically involve the formation of a diazo‐based carbene precursor, but procedures using diazo‐free metal carbenes have been developed with significant success. This Minireview covers transition‐metal catalyzed insertion reactions with donor/donor and donor carbenes, providing context for future developments in this emerging field.

Six-membered ring oxygen and nitrogen heterocycles are formed stereoselectively by C–H insertion of donor/donor carbenes.

Donor/donor carbenes are relatively new in the field of carbene chemistry; although applications in C−H and X−H insertion reactions are few in number, they demonstrate exquisite chemo‐ and stereo‐selectivity. Recent reports have shown that C−H, N−H, B−H, O−H, S−H, Si−H, Ge−H, Sn−H and P−H insertion reactions are feasible with a variety of transition metal catalysts, both inter‐ and intramolecularly. Furthermore, high degrees of diastereo‐ and enantioselectivity have been observed in several cases. Methods typically involve the formation of a diazo‐based carbene precursor, but procedures using diazo‐free metal carbenes have been developed with significant success. This Minireview covers transition‐metal catalyzed insertion reactions with donor/donor and donor carbenes, providing context for future developments in this emerging field.

Panowamycins are a group of isochromanbased natural products first isolated from Streptomyces sp. K07-0010 in 2012 by Satoshi Ōmura and co-workers that exhibit modest anti-trypanosomal activity. Herein we demonstrate the first syntheses of these natural products and their epimers. Stereoselective dirhodiumcatalyzed CÀ H insertion reactions with a donor/donor carbene construct the substituted isochroman core in the key bond-forming step. The syntheses are completed without the use of protecting groups and feature a latestage Wacker oxidation. Incongruent NMR spectra between natural and synthetic samples revealed the structural misassignment of panowamycin A and veramycin F. Computational NMR studies suggested panowamycin A to be an alternate diastereomer, which was confirmed by synthesizing this isomer. Concurrent with this work, in 2021 Mahmud and co-workers came to the same conclusion with an updated NMR analysis of panowamycin A. In a divergent, asymmetric sequence, we report the synthesis of panowamycin A, panowamycin B, TM-135, and veramycin F.