819050-89-0

Upstream product

• 819050-88-9 α,α,α′,α′-tetramethyl-1,3 benzenedipropionic acid 
• 626-16-4 3-(chloromethyl)benzyl chloride 

Relevant academic research and scientific papers

Characterization of a reactive Rh2 nitrenoid by crystalline matrix isolation

The fleeting lifetimes of reactive intermediates in C-H functionalization chemistry often prevent their direct characterization. For example, the critical nitrenoid intermediates that mediate Rh2-catalyzed C-H amination have eluded characterization for more than 40 years. In the absence of structural characterization of these species, methodological development is often computationally guided. Here we report the first X-ray crystal structure of a reactive Rh2 nitrenoid, enabled by N2 elimination from an organic azide ligand within a single-crystal matrix. The resulting high-resolution structure displays metrical parameters consistent with a triplet nitrene complex of Rh2. The demonstration of facile access to reactive metal nitrenoids within a crystalline matrix provides a platform for structural characterization of the transient species at the heart of C-H functionalization.

Scalable Synthesis of Esp and Rhodium(II) Carboxylates from Acetylacetone and RhCl3· xH2O

Rhodium(II) carboxylates are privileged catalysts for the most challenging carbene-, nitrene-, and oxo-transfer reactions. In this work, we address the strategic challenges of current organic and inorganic synthesis methods to access these rhodium(II) complexes through an oxidative rearrangement strategy and a reductive ligation reaction. These studies illustrate the multiple benefits of oxidative rearrangement in the process-scale synthesis of congested carboxylates over nitrile anion alkylation reactions, and the impressive effect of inorganic additives in the reductive ligation of rhodium(III) salts.

PROCESSES FOR PREPARING COMPLEXES COMPRISING RHODIUM(II) AND CARBOXYLATE LIGANDS

There is provided herein a process for the preparation of a complex of formula (I): Rh(II)2 Xn, wherein X and n have meanings provided in the description, comprising the step of reacting: (a) a source of Rh(III); and (b) a source of

Rh(ii)-Catalyzed formation of pyrrolo[2,3-b]quinolines from azide-methylenecyclopropanes and isonitriles

Azide-methylenecyclopropanes (azide-MCPs) underwent an intermolecular cyclization with isonitriles catalyzed by a RhII complex to produce a series of pyrrolo[2,3-b]quinolines in moderate to good yields via carbodiimide intermediates. Moreover, synthetic applications of these products to construct structurally novel and useful heterocycles have also been achieved.

Dirhodium catalysts that bear redox noninnocent chelating dicarboxylate ligands and their performance in intra-and intermolecular C-H amination

We report two new analogues of the well-known C-H amination catalyst [Rh2(esp)2] (1) (esp = α,α,α′, α′-tetramethyl-1,3-benzenedipropanoate) that bear redox-active supporting ligands that are structurally similar to esp. The redox-active ligands are 2-[3-(1-carboxy-1-methylethoxy)phenoxy]-2-methylpropanoic acid (H2L1) and (3-methoxycarbonyl-2,5-di-tert-butylphenoxy)ethanoic acid (H2L2), which react with Rh2(OAc)4 to form the catalysts [Rh2(L1)2] (2) and [Rh2(L2) 2] (3). Both 2 and 3 have been characterized by X-ray crystallography and cyclic voltammetry, inter alia. Compounds 2 and 3 are structurally similar to 1 but show more complex electrochemical features. Whereas 1 has a single reversible redox wave that corresponds to the Rh2II,II/ Rh2II,III couple, 2 and 3 show multiple oxidations that are characteristic of ligand-centered oxidation. Catalysts 1, 2, and 3 perform well in a model intramolecular C-H amination reaction, and all three catalysts perform equally well during the first four hours of a model intermolecular reaction. After this point, 2 and 3 cease to function, whereas 1 continues to be active. These results support the hypothesis that intermolecular C-H amination utilizes two distinct mechanisms: (1) a nitrene interception/insertion mechanism that is fast but ceases to be operative after four hours, and (2) a one-electron mechanism that is more robust over extended time periods, but requires the catalyst to be able to undergo Rh2-centered oxidation. Copyright

Catalytic intermolecular amination of C-H bonds: Method development and mechanistic insights

Reaction methodology for intermolecular C-H amination of benzylic and 3° C-H bonds is described. This process uses the starting alkane as the limiting reagent, gives optically pure tetrasubstituted amines through stereospecific insertion into enantiomeric 3° centers, displays high chemoselectivity for benzylic oxidation, and enables the facile preparation of isotopically enriched 15N-labeled compounds. Access to substituted amines, amino alcohols, and diamines is thereby made possible in a single transformation. Important information relevant to understanding the initial steps in the catalytic cycle, reaction chemoselectivity, the nature of the active oxidant, and pathways for catalyst inactivation has been gained through mechanistic analysis; these studies are also presented.

Expanding the scope of C-H amination through catalyst design

Analysis of the mechanism for Rh-mediated C-H amination has led to the development of a remarkably effective dinuclear Rh catalyst derived from 1,3-benzenedipropionic acid. This unique complex, Rh2(esp)2, is capable of promoting both