José-Antonio García-López

Trapping σ‐Alkyl–Palladium(II) Intermediates with Arynes Encompassing Intramolecular C−H Activation: Spirobiaryls through Pd‐Catalyzed Cascade Reactions

A palladium-catalyzed cascade reaction based on the trapping of transient alkyl-PdII intermediates with arynes encompassing a C-H activation step has been developed. This synthetic pathway gives rise to hetero-spirocyclic scaffolds containing a biaryl motif, and opens up new synthetic strategies in the design of cascade reactions since it gathers several aspects of Pd chemistry, i.e., intra- and intermolecular carbopalladation of unsaturated species, C-H activation and C-C coupling processes.

Synthesis of biaryls using aryne intermediates

The synthesis of biaryls from benzyne intermediates offers an alternative strategy to conventional metal-catalyzed cross-coupling approaches. The concept is as old as benzyne itself, being the basis of Wittigs seminal observations on biphenyl synthesis from phenyl lithium and fluorobenzene in 1940. In the intervening 75 years, the transformation has grown to encompass a remarkable scope of reaction classes, and continues to develop as new benzyne precursors enable inventive biaryl syntheses under mild conditions. This review will cover all aryne methods relevant to biaryl synthesis, drawing together key ideas from the older literature involving halobenzene precursors, with a more comprehensive coverage of modern methods using 2-(trimethylsilyl)phenyl triflates and tri-ynes as the source of benzyne. Collectively, we hope to highlight the power of aryne chemistry to access a huge range of biaryl structures from a versatile and highly customizable set of substrates.

σ‐Alkyl‐PdII Species for Remote C−H Functionalization

The transition‐metal‐directed C−H activation processes have traditionally required the installation of suitable coordinating groups to place the metal in close proximity to an specific neighboring or remote C(sp2)‐H or C(sp3)‐H moiety of the molecular structure. Alternatively, substitution of C−H bonds at positions previously thought inaccessible are now performed through domino processes via in situ generated σ‐alkyl‐PdII species. This Concept article highlights on recent developments which utilize these σ‐alky‐PdII‐species for remote C−H functionalization to reinvigorate new C−C bond formation in cascade fashion via use of catalytic palladium metal.

CCDC 1574288: Experimental Crystal Structure Determination

Related Article: Marta Perez-Gomez, Leticia Navarro, Isabel Saura-Llamas, Delia Bautista, Mark Lautens, Jose-Antonio Garcia-Lopez|2017|Organometallics|36|4465|doi:10.1021/acs.organomet.7b00702

CCDC 1574289: Experimental Crystal Structure Determination

Related Article: Marta Perez-Gomez, Leticia Navarro, Isabel Saura-Llamas, Delia Bautista, Mark Lautens, Jose-Antonio Garcia-Lopez|2017|Organometallics|36|4465|doi:10.1021/acs.organomet.7b00702