Development of potent inhibitors for strigolactone receptor DWARF 14

Strigolactones (SLs) are plant hormones that suppress shoot branching through perception by their receptor protein DWARF 14 (D14). The artificial regulation of SL signaling has been considered a potent agricultural technique because plant architecture is strongly related to crop yield. In this communication, we describe the development of a small-molecule D14 inhibitor that functions at sub-micromolar levels. This potent inhibitor may be a lead compound for a first-in-class plant growth regulator.

Ester dance reaction on the aromatic ring

Aromatic rearrangement reactions are useful tools in the organic chemist's toolbox when generating uncommon substitution patterns. However, it is difficult to precisely translocate a functional group in (hetero) arene systems, with the exception of halogen atoms in a halogen dance reaction. Here, we describe an unprecedented "ester dance" reaction: a predictable translocation of an ester group from one carbon atom to another on an aromatic ring. Specifically, a phenyl carboxylate substituent can be shifted from one carbon to an adjacent carbon on a (hetero) aromatic ring under palladium catalysis to often give a thermodynamically favored, regioisomeric product with modest to good conversions. The obtained ester moiety can be further converted to various aromatic derivatives through the use of classic and state-of-the-art transformations including amidation, acylations, and decarbonylative couplings.

Pd-Catalyzed Decarbonylative C-H Coupling of Azoles and Aromatic Esters

A decarbonylative C-H coupling of azoles and aromatic esters by palladium catalysis is described. Our previously reported Ni-catalyzed C-H coupling of azoles and aromatic esters has a significant drawback regarding the substrate scope. Herein, we employ palladium catalysis instead of nickel, resulting in a broader substrate scope in terms of azoles and aromatic esters.

Cross-coupling of aromatic esters and amides

Catalytic cross-coupling reactions of aromatic esters and amides have recently gained considerable attention from synthetic chemists as de novo and efficient synthetic methods to form C-C and C-heteroatom bonds. Esters and amides can be used as diversifiable groups in metal-catalyzed cross-coupling: in a decarbonylative manner, they can be utilized as leaving groups, whereas in a non-decarbonylative manner, they can form ketone derivatives. In this review, recent advances of this research topic are discussed.

Dynamic Ligand Exchange as a Mechanistic Probe in Pd-Catalyzed Enantioselective C-H Functionalization Reactions Using Monoprotected Amino Acid Ligands

A new tool for probing enantioselective reaction mechanisms is introduced. Monitoring the temporal change in product enantiomeric excess after addition of the opposite enantiomer of the ligand during the reaction provides a means of probing dynamic ligand exchange in enantioselective C-H iodination catalyzed by Pd with monoprotected amino acid ligands (MPAAs). This work has general potential to provide insights about the dynamics of catalyst and ligand molecularity and exchange.

Catalytic α-Arylation of Ketones with Heteroaromatic Esters

Heteroaromatic esters were found to be applicable as an arylating agent for the Pd-catalyzed α-arylation of ketones in a decarbonylative fashion. The use of our in-house ligand, dcypt, enabled this unique bond formation. Considering the ubiquity and low cost of ­aromatic esters, the present work will allow for rapid access to valuable α-aryl carbonyl compounds.

Ligand-Promoted Borylation of C(sp(3))-H Bonds with Palladium(II) Catalysts

A quinoline-based ligand effectively promotes the palladium-catalyzed borylation of C(sp(3))-H bonds. Primary β-C(sp(3))-H bonds in carboxylic acid derivatives as well as secondary C(sp(3))-H bonds in a variety of carbocyclic rings, including cyclopropanes, cyclobutanes, cyclopentanes, cyclohexanes, and cycloheptanes, can thus be borylated. This directed borylation method complements existing iridium(I)- and rhodium(I)-catalyzed C-H borylation reactions in terms of scope and operational conditions.

Ligand-enabled cross-coupling of C(sp(3))-H bonds with arylsilanes

Pd(II)-catalyzed cross-coupling of C(sp(3))-H bonds with organosilicon coupling partners has been achieved for the first time. The use of a newly developed quinoline-based ligand is essential for the cross-coupling reactions to proceed.

Ni-Catalyzed α-arylation of esters and amides with phenol derivatives

A nickel-catalyzed α-arylation of esters and amides with phenol derivatives has been accomplished. In the presence of our unique nickel catalyst, prepared in situ from Ni(cod)2, 3,4-bis(dicyclohexylphosphino)thiophene (dcypt), and K3PO4, various esters and amides undergo α-arylation with O-arylpivalates or O-arylcarbamates to afford the corresponding coupling products. The thus obtained α-aryl esters and amides are useful precursors of privileged motifs such as α-arylcarboxylic acids and β-arylamines.

Nickel-catalyzed α-arylation of ketones with phenol derivatives

The nickel-catalyzed α-arylation of ketones with readily available phenol derivatives (esters and carbamates) provides access to useful α-arylketones. For this transformation, 3,4-bis(dicyclohexylphosphino)thiophene (dcypt) was identified as a new, enabling, air-stable ligand for this transformation. The intermediate of an assumed C-O oxidative addition was isolated and characterized by X-ray crystal-structure analysis.