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Rhodium^III-catalyzed remote difunctionalization of arenes assisted by a relay directing group.

ABSTRACT: Rhodium-catalyzed diverse tandem twofold C-H bond activation reactions of para-olefin-tethered arenes have been realized, with unsaturated reagents such as internal alkynes, dioxazolones, and isocyanates being the coupling partner as well as a relay directing group which triggers cyclization of the para-olefin group under oxidative or redox-neutral conditions. The reaction proceeded via initial ortho-C-H activation assisted by a built-in directing group in the arene, and the ortho-incorporation of the unsaturated coupling partner simultaneously generated a relay directing group that allows sequential C-H activation at the meta-position and subsequent cyclization of the para-olefins. The overall reaction represents C-C or N-C difunctionalization of the arene with the generation of diverse 2,3-dihydrobenzofuran platforms. The catalytic system proceeded with good efficiency, simple reaction conditions, and broad substrate scope. The diverse transformations of the products demonstrated the synthetic utility of this tandem reaction.

SUBMITTER: Sun L

PROVIDER: S-EPMC9214915 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Directing group assisted rhodium catalyzed meta-C–H alkynylation of arenes† † Electronic supplementary information (ESI) available. See https://doi.org/10.1039/d2sc00982j

Project description:Site-selective C–H alkynylation of arenes to produce aryl alkynes is a highly desirable transformation due to the prevalence of aryl alkynes in various natural products, drug molecules and in materials. To ensure site-selective C–H functionalization, directing group (DG) assisted C–H activation has been evolved as a useful synthetic tool. In contrast to DG-assisted ortho-C–H activation, distal meta-C–H activation is highly challenging and has attracted significant attention in recent years. However, developments are majorly focused on Pd-based catalytic systems. In order to diversify the scope of distal meta-C–H functionalization, herein we disclosed the first Rh(i) catalyzed meta-C–H alkynylation protocol through the inverse Sonogashira coupling reaction. The protocol is compatible with various substrate classes which include phenylacetic acids, hydrocinnamic acids, 2-phenyl benzoic acids, 2-phenyl phenols, benzyl sulfonates and ether-based scaffolds. The post-synthetic modification of meta-alkynylated arenes is also demonstrated through DG-removal as well as functional group interconversion. An unprecedented report on Rh-catalyzed meta-C–H alkynylation of arenes, aided by a weakly coordinating cyano-based directing template, was developed using bromoalkynes as the coupling partner.

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Rhodium(iii)-catalyzed diverse [4 + 1] annulation of arenes with 1,3-enynes via sp3/sp2 C-H activation and 1,4-rhodium migration.

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Project description: Not available

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Photo-Induced Ruthenium-Catalyzed Double Remote C(sp2 )-H / C(sp3 )-H Functionalizations by Radical Relay.

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| S-EPMC9401009 | biostudies-literature

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Project description:The design of stereodivergent transformations is of great interest to the synthetic community as it allows funneling of a given reaction pathway toward one stereochemical outcome or another by only minor adjustments of the reaction setup. Herein, we present a physical organic approach to invert the sense of induction in diastereoselective cyclopropanation of alkenes with N-enoxyphthalimides through rhodium(III) catalysis. Careful parametrization of catalyst-substrate molecular determinants allowed us to interrogate linear-free energy relationships and establish an intuitive and robust statistical model that correlates an extensive number of data points in high accuracy. Our multivariate correlations-steered mechanistic investigation culminated with a robust and general diastereodivergent cyclopropanation tool where the switch from trans- to cis-diastereoinduction is attributed to a mechanistic dichotomy. Selectivity might be determined by the flexibility of rhodacyclic intermediates derived from ring-opened versus -unopened phthalimides, induced by both their respective ring size and the Sterimol B1 parameter of the CpX ligand on rhodium.

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