Published in Tetrahedron Letters
A new, concise synthesis of the CCR-5 receptor antagonist maraviroc (UK-427,857) from 3-phenyl-1-propanol has been completed in four steps featuring a site-selective C–H functionalization.
Published in Advances in Chemical Engineering and Science
We outline a strategy to enable non-directed Pd(II)-catalyzed C-H functionalization in the presence of Lewis basic heterocycles. In a high-throughput screen of two Pd-catalyzed C-H acetoxylation reactions, addition of a variety of N-containing heterocycles is found to cause low product conversion. A pyridine-containing test substrate is selected as...
Published in Journal of the American Chemical Society
Predicting site selectivity in C-H bond oxidation reactions involving heteroatom transfer is challenged by the small energetic differences between disparate bond types and the subtle interplay of steric and electronic effects that influence reactivity. Herein, the factors governing selective Rh2(esp)2-catalyzed C-H amination of isoamylbenzene deriv...
Published in Journal of the American Chemical Society
The synthesis of 1,2-diamines has been achieved through a single-step, tandem sequence involving Rh-catalyzed aziridination followed by NaI-promoted rearrangement to an isomeric cyclic sulfamide. Facile ring opening of these products in hot water and pyridine affords differentially protected vicinal diamines. Demonstration of the utility of this me...
Published in Advances in Chemical Engineering and Science
Mechanistic insight into a C–H hydroxylation reaction catalysed by [(Me3tacn)RuCl3] has been obtained using desorption electrospray ionization mass spectrometry (DESI-MS) to identify reactive intermediates and to determine the fate of the starting metal complex. Our studies provide direct evidence for the formation of a high-valent dioxo-Ru(VI) spe...
Published in Advances in Chemical Engineering and Science
Selective hydroxylation of 3° and benzylic C–H bonds is made possible using a non-metal-based catalyst system, Oxone as the terminal oxidant, and an aqueous fluoroalcohol solvent mixture. The choice of solvent is uniquely effective for this process, but seemingly at odds with our finding that H2O promotes reduction of the oxaziridine intermediate. ...
Published in Angewandte Chemie International Edition in English
C-H insertion: A method for intermolecular amination of tertiary CH bonds is described that uses limiting amounts of substrate and a convenient phenol-derived nitrogen source. Structure-selectivity and mechanistic studies suggest that steric interaction between the substrate and active oxidant is the principal determinant of product selectivity.
Published in Proceedings of the Latvian Academy of Sciences Section B Natural Exact and Applied Sciences
We have applied an ambient ionization technique, desorption electrospray ionization MS, to identify transient reactive species of an archetypal C-H amination reaction catalyzed by a dirhodium tetracarboxylate complex. Using this analytical method, we have detected previously proposed short-lived reaction intermediates, including two nitrenoid compl...
Published in Organic and Medicinal Chemistry Letters
A general, high yielding method for the synthesis of 1,2-diamine derivatives is described that capitalizes on selective, rhodium-catalyzed C-H insertion of hydroxylamine-based sulfamate esters. The resulting Troc-protected oxathiadiazinane heterocycles are easily modified and can be reduced under the mild action of NaI to afford differentially subs...
Published in Accounts of Chemical Research
For more than a century, chemists have endeavored to discover and develop reaction processes that enable the selective oxidation of hydrocarbons. In the 1970s, Abramovitch and Yamada described the synthesis and electrophilic reactivity of sulfonyliminoiodinanes (RSO(2)N═IPh), demonstrating the utility of this new class of reagents to function as ni...
Published in Organic Process Research & Development
Reaction methods for selective C–H amination are finding ever-increasing utility for the preparation of nitrogen-derived fine chemicals. This brief account highlights the remarkable versatility of dirhodium-based catalysts for promoting oxidation of aliphatic C–H centers in both intra- and intermolecular reaction processes.
Published in Journal of the American Chemical Society
The mixed-valent paddlewheel complex tetrakis(2-oxypyridinato) diruthenium (II,III) chloride, [Ru(2)(hp)(4)Cl], catalyzes intramolecular allylic C-H amination with bis(homoallylic) sulfamate esters. These results stand in marked contrast to reactions performed with dirhodium catalysts, which favor aziridine products. The following discussion consti...
Published in Quarterly Reviews Chemical Society
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Published in Topics in Current Chemitry
This chapter offers a general review of selective methods for the oxidative conversion of C–H to C–N bonds. Special focus has been given to the many disparate catalyst types that are capable of promoting this unique transformation.
Published in Journal of the American Chemical Society
The use of a bifunctional nitrogen nucleophile and an allyl carbonate starting material in successive enantioselective palladium- and diastereoselective rhodium-catalyzed reactions enables the rapid assembly of unique amino aziridine products. Further elaboration of these materials affords complex, stereodefined polyamine architectures, thus demons...
