Biomimetic 2-Imino-Nazarov Cyclizations via Eneallene Aziridination

Journal of the American Chemical Society · 2020 · 27 citations

• Chemistry
• Combinatorial chemistry
• Stereochemistry

complex as both a nitrene transfer catalyst and a Lewis acid promoter, insight that provides a framework for the future development of asymmetric 2-imino-Nazarov cyclizations.

Investigation of transition metal-catalyzed nitrene transfer reactions in water

Bioorganic & Medicinal Chemistry · 2018-04-11 · 19 citations

Method for Small-Scale Production of Deuterochloroform

The Journal of Organic Chemistry · 2018-06-04 · 4 citations

Deuterochloroform (CDCl3) is a common deuterated solvent for nuclear magnetic resonance (NMR) analyses. The synthesis of significant amounts of CDCl3 for both research use and large undergraduate organic laboratories in a safe and inexpensive manner is appealing. Herein, we describe a convenient laboratory scale preparation of CDCl3 that employs a reduction and decarboxylation of hexachloro-2-propanone (HCP) catalyzed by various pyridines. A PVP catalyst gives cleaner reaction and greater catalyst stability through multiple rounds of recycling, justifying its higher cost compared to pyridine.

Tunable differentiation of tertiary C–H bonds in intramolecular transition metal-catalyzed nitrene transfer reactions

Chemical Communications · 2017-01-01 · 34 citations

(ii) complexes expands the scope of successful catalyst-controlled intramolecular nitrene transfer and represents a promising springboard for the future development of intermolecular C-H N-group transfer methods.

Tunable, Chemo- and Site-Selective Nitrene Transfer Reactions through the Rational Design of Silver(I) Catalysts

Accounts of Chemical Research · 2017-08-08 · 178 citations

ConspectusCarbon–nitrogen (C–N) bonds are ubiquitous in pharmaceuticals, agrochemicals, diverse bioactive natural products, and ligands for transition metal catalysts. An effective strategy for introducing a new C–N bond into a molecule is through transition metal-catalyzed nitrene transfer chemistry. In these reactions, a metal–supported nitrene can either add across a C═C bond to form an aziridine or insert into a C–H bond to furnish the corresponding amine. Typical catalysts for nitrene transfer include Rh2Ln and Ru2Ln complexes supported by bridging carboxylate and related ligands, as well as complexes based on Cu, Co, Ir, Fe, and Mn supported by porphyrins and related ligands.A limitation of metal-catalyzed nitrene transfer is the ability to predictably select which specific site will undergo amination in the presence of multiple reactive groups; thus, many reactions rely primarily on substrate control. Achieving true catalyst-control over nitrene transfer would open up exciting possibilities for flexible installation of new C–N bonds into hydrocarbons, natural product-inspired scaffolds, existing pharmaceuticals or biorenewable building blocks.Silver-catalyzed nitrene transfer enables flexible control over the position at which a new C–N bond is introduced. Ag(I) supported by simple N-donor ligands accommodates a diverse range of coordination geometries, from linear to tetrahedral to seesaw, enabling the electronic and steric parameters of the catalyst to be tuned independently. In addition, the ligand, Ag salt counteranion, Ag/ligand ratio and the solvent all influence the fluxional and dynamic behavior of Ag(I) complexes in solution. Understanding the interplay of these parameters to manipulate the behavior of Ag-nitrenes in a predictable manner is a key design feature of our work. In this Account, we describe successful applications of a variety of design principles to tunable, Ag-catalyzed aminations, including (1) changing Ag/ligand ratios to influence chemoselectivity, (2) manipulating the steric environment of the catalyst to achieve site-selective C–H bond amination, (3) promoting noncovalent interactions between Ag/substrate or substrate/ligand to direct C–H functionalization, and (4) dictating the substrate's trajectory of approach to the Ag-nitrene. Our catalysts distinguish between the aminations of various types of C–H bonds, including tertiary C(sp3)–H, benzylic, allylic, and propargylic C–H bonds. Efforts in asymmetric nitrene transfer reactions catalyzed by Ag(I) complexes are also described.

Synthesis, Characterization, and Variable-Temperature NMR Studies of Silver(I) Complexes for Selective Nitrene Transfer

Inorganic Chemistry · 2017-05-16 · 51 citations

An array of silver complexes supported by nitrogen-donor ligands catalyze the transformation of C═C and C–H bonds to valuable C–N bonds via nitrene transfer. The ability to achieve high chemoselectivity and site selectivity in an amination event requires an understanding of both the solid- and solution-state behavior of these catalysts. X-ray structural characterizations were helpful in determining ligand features that promote the formation of monomeric versus dimeric complexes. Variable-temperature 1H and DOSY NMR experiments were especially useful for understanding how the ligand identity influences the nuclearity, coordination number, and fluxional behavior of silver(I) complexes in solution. These insights are valuable for developing improved ligand designs.