Nicholas S. Dolan

Bio: Nicholas S. Dolan is an academic researcher from University of Wisconsin-Madison. The author has contributed to research in topics: Nitrene & Chemoselectivity. The author has an hindex of 5, co-authored 7 publications receiving 263 citations.

Catalyst-Controlled and Tunable, Chemoselective Silver-Catalyzed Intermolecular Nitrene Transfer: Experimental and Computational Studies

Abstract: The development of new catalysts for selective nitrene transfer is a continuing area of interest. In particular, the ability to control the chemoselectivity of intermolecular reactions in the presence of multiple reactive sites has been a long-standing challenge in the field. In this paper, we demonstrate examples of silver-catalyzed, nondirected, intermolecular nitrene transfer reactions that are both chemoselective and flexible for aziridination or C–H insertion, depending on the choice of ligand. Experimental probes present a puzzling picture of the mechanistic details of the pathways mediated by [(tBu3tpy)AgOTf]2 and (tpa)AgOTf. Computational studies elucidate these subtleties and provide guidance for the future development of new catalysts exhibiting improved tunability in group transfer reactions.

Ligand-Controlled, Tunable Silver-Catalyzed C–H Amination

Abstract: The development of readily tunable and regioselective C–H functionalization reactions that operate solely through catalyst control remains a challenge in modern organic synthesis. Herein, we report that simple silver catalysts supported by common nitrogenated ligands can be used to tune a nitrene transfer reaction between two different types of C–H bonds. The results reported herein represent the first example of ligand-controlled and site-selective silver-promoted C–H amination.

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

Abstract: 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.

Transition Metal-Catalyzed C–H Amination: Scope, Mechanism, and Applications

Abstract: Catalytic transformation of ubiquitous C–H bonds into valuable C–N bonds offers an efficient synthetic approach to construct N-functionalized molecules. Over the last few decades, transition metal catalysis has been repeatedly proven to be a powerful tool for the direct conversion of cheap hydrocarbons to synthetically versatile amino-containing compounds. This Review comprehensively highlights recent advances in intra- and intermolecular C–H amination reactions utilizing late transition metal-based catalysts. Initial discovery, mechanistic study, and additional applications were categorized on the basis of the mechanistic scaffolds and types of reactions. Reactivity and selectivity of novel systems are discussed in three sections, with each being defined by a proposed working mode.

New Strategies for the Transition-Metal Catalyzed Synthesis of Aliphatic Amines.

Abstract: Transition-metal catalyzed reactions that are able to construct complex aliphatic amines from simple, readily available feedstocks have become a cornerstone of modern synthetic organic chemistry. I...

Transition metal-catalyzed site- and regio-divergent C–H bond functionalization

Abstract: Recent advances in transition metal-catalyzed C–H bond functionalization have profoundly impacted synthetic strategy Since organic substrates typically contain several chemically distinct C–H bonds, controlling the regioselectivity of C–H bond functionalization is imperative to harness its full potential Moreover, the ability to alter reaction pathways to selectively functionalize different C–H bonds in a substrate represents a greater opportunity and challenge The choice of catalysts, ligands, solvents, and even more subtle variations of the reaction conditions have been shown to allow the formation of regioisomeric C–H functionalization products starting from the same precursors This review describes recent advances in transition metal-catalyzed divergent C–H bond functionalization that highlight its potential in organic synthesis

Ag-catalyzed C–H/C–C bond functionalization

Abstract: Silver, known and utilized since ancient times, is a coinage metal, which has been widely used for various organic transformations in the past few decades. Currently, the silver-catalyzed reaction is one of the frontier areas in organic chemistry, and the progress of research in this field is very rapid. Compared with other transition metals, silver has long been believed to have low catalytic efficiency, and most commonly, it is used as either a cocatalyst or a Lewis acid. Interestingly, the discovery of Ag-catalysis has been significantly improved in recent years. Especially, Ag(I) has been demonstrated as an important and versatile catalyst for a variety of organic transformations. However, so far, there has been no systematic review on Ag-catalyzed C–H/C–C bond functionalization. In this review, we will focus on the development of Ag-catalyzed C–H/C–C bond functionalization and the corresponding mechanism.

Selective formation of γ-lactams via C–H amidation enabled by tailored iridium catalysts

Abstract: Intramolecular insertion of metal nitrenes into carbon-hydrogen bonds to form γ-lactam rings has traditionally been hindered by competing isocyanate formation. We report the application of theory and mechanism studies to optimize a class of pentamethylcyclopentadienyl iridium(III) catalysts for suppression of this competing pathway. Modulation of the stereoelectronic properties of the auxiliary bidentate ligands to be more electron-donating was suggested by density functional theory calculations to lower the C–H insertion barrier favoring the desired reaction. These catalysts transform a wide range of 1,4,2-dioxazol-5-ones, carbonylnitrene precursors easily accessible from carboxylic acids, into the corresponding γ-lactams via sp 3 and sp 2 C–H amidation with exceptional selectivity. The power of this method was further demonstrated by the successful late-stage functionalization of amino acid derivatives and other bioactive molecules.