Search

Transition metal-catalyzed transfers of carbenes, nitrenes, and oxenes are powerful methods for functionalizing C=C and C-H bonds. Nature has evolved a diverse toolbox for oxene transfers, as exemplified by the myriad monooxygenation reactions catalyzed by cytochrome P450 enzymes. The isoelectronic carbene transfer to olefins, a widely used C-C bond-forming reaction in organic synthesis, has no biological counterpart. Here we report engineered variants of cytochrome P450BM3 that catalyze highly diastereo- and enantioselective cyclopropanation of styrenes from diazoester reagents via putative carbene transfer. This work highlights the capacity to adapt existing enzymes for the catalysis of synthetically important reactions not previously observed in nature. [ABSTRACT FROM AUTHOR]

The authors discuss reports within the issue by J. C. Tellis et al. and Z. Zuo et al. on iridium photocatalysts to supply reactive radical coupling partners (R•) to a nickel (Ni)-catalyzed carbon-carbon (C-C) bond-forming process. A discussion of the challenges of coupling reactions in carbon compounds with four single bonds (Csp3) and a schematic representation of iridium and nickel catalytic cycles for the cross-coupling of a stable radical precursor are presented.

The authors comment on a report within the issue by S. Krautwald and team on the use of two independent, synergistic chiral catalysts for the stereodivergent dual catalysis of the α-allylation of branched aldehydes. The researchers used an iridium catalyst to activate the allylic electrophilic substrate and an amine catalyst to activate the aldehyde substrate in the carbon-carbon bond forming reaction. This method allows for the separate control of stereoselectivity in each substrate, which enables the production of all four potential stereoisomers in one reaction.

The article comments on a report within the issue by researcher J. T. Malinowski and colleagues which describes a simplified method for the chemical synthesis of the natural product pactamycin. The team found a symmetric region of the pactamycin which allowed the formation of carbon-carbon bonds using the Mannich reaction with a chiral amine catalyst. Other topics include stereochemical regulation, methyl ketone reductive desymmetrization, and potential uses of reaction intermediates as precursors for therapeutic analogs.