A theory-driven synthesis of symmetric and unsymmetric 1,2-bis(diphenylphosphino)ethane analogues via radical difunctionalization of ethylene.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36411284.
- Also identified by DOI 10.1038/s41467-022-34546-5 and PMC identifier 9678890.
- Licence recorded as CC BY.
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Abstract
1,2-Bis(diphenylphosphino)ethane (DPPE) and its synthetic analogues are important structural motifs in organic synthesis, particularly as diphosphine ligands with a C<sub>2</sub>-alkyl-linker chain. Since DPPE is known to bind to many metal centers in a bidentate fashion to stabilize the corresponding metal complex via the chelation effect originating from its entropic advantage over monodentate ligands, it is often used in transition-metal-catalyzed transformations. Symmetric DPPE derivatives (Ar<sup>1</sup><sub>2</sub>P-CH<sub>2</sub>-CH<sub>2</sub>-PAr<sup>1</sup><sub>2</sub>) are well-known and readily prepared, but electronically and sterically unsymmetric DPPE (Ar<sup>1</sup><sub>2</sub>P-CH<sub>2</sub>-CH<sub>2</sub>-PAr<sup>2</sup><sub>2</sub>; Ar<sup>1</sup>≠Ar<sup>2</sup>) ligands have been less explored, mostly due to the difficulties associated with their preparation. Here we report a synthetic method for both symmetric and unsymmetric DPPEs via radical difunctionalization of ethylene, a fundamental C<sub>2</sub> unit, with two phosphine-centered radicals, which is guided by the computational analysis with the artificial force induced reaction (AFIR) method, a quantum chemical calculation-based automated reaction path search tool. The obtained unsymmetric DPPE ligands can coordinate to several transition-metal salts to form the corresponding complexes, one of which exhibits distinctly different characteristics than the corresponding symmetric DPPE-metal complex.