Search for: All records

In this study, we investigate the reactivity of nitrous oxide (N₂O) with lithiated diarylmethylhydrazines, leading to the formation of diarylethanesviadinitrogen extrusion. 

Given the prevalence of nitrogen-containing heterocycles in commercial drugs, selectively incorporating a single nitrogen atom is a promising scaffold hopping approach to enhance chemical diversity in drug discovery libraries. We harness the distinct reactivity of sulfenylnitrenes, which insert a single nitrogen atom to transform readily available pyrroles, indoles, and imidazoles into synthetically challenging pyrimidines, quinazolines, and triazines, respectively. Our additive-free method for skeletal editing employs easily accessible, benchtop-stable sulfenylnitrene precursors over a broad temperature range (−30 to 150°C). This approach is compatible with diverse functional groups, including oxidation-sensitive functionalities such as phenols and thioethers, and has been applied to various natural products, amino acids, and pharmaceuticals. Furthermore, we have conducted mechanistic studies and explored regioselectivity outcomes through density functional theory calculations. 

1,2-cis-Furanosides are present in various biomedically relevant glycosides, and their stereoselective synthesis remains a significant challenge. In this vein, we have developed a stereoselective approach to 1,2-cis-furanosylations using earth-abundant copper catalysis. This protocol proceeds under mild conditions at room temperature and employs readily accessible benchtop stable enynalderived furanose donors. This chemistry accommodates a variety of alcohols, including primary, secondary, and tertiary, as well as mannosyl alcohol acceptors, which have been incompatible with most known methods of furanosylation. The resulting 1,2-cisfuranoside products exhibit high yields and anomeric selectivity with both the ribose and arabinose series. Furthermore, the anomeric selectivity is independent of the C2 oxygen-protecting group and the anomeric configuration of the starting donor. Experimental evidence and computational studies support our hypothesis that copper chelation between the C2 oxygen of the furanose donor and an incoming alcohol nucleophile is responsible for the observed 1,2-cisstereoselectivity. 

Dioxomolybdenum complexes based on salan ligands have been evaluated for their potential in catalyzing the deoxydehydration (DODH) reaction. The DODH reaction is a formal reduction that converts vicinal diols into... 

Abstract Catalysis ofO‐atom transfer (OAT) reactions is a characteristic of both natural (enzymatic) and synthetic molybdenum‐oxo and ‐peroxo complexes. These reactions can employ a variety of terminal oxidants, e. g. DMSO,N‐oxides, and peroxides, etc., but rarely molecular oxygen. Here we demonstrate the ability of a set of Schiff‐base‐MoO₂complexes (cy‐salen)MoO₂(cy‐salen=N,N’‐cyclohexyl‐1,2‐bis‐salicylimine) to catalyze the aerobic oxidation of PPh₃. We also report the results of a DFT computational investigation of the catalytic pathway, including the identification of energetically accessible intermediates and transition states, for the aerobic oxidation of PMe₃. Starting from the dioxo species, (cy‐salen)Mo(VI)O₂(1), key reaction steps include: 1) associative addition of PMe₃to an oxo‐O to give LMo(IV)(O)(OPMe₃) (2); 2) OPMe₃dissociation from2to produce mono‐oxo complex (cy‐salen)Mo(IV)O (3); 3) stepwise O₂association with3via superoxo species (cy‐salen)Mo(V)(O)(η¹‐O₂) (4) to form the oxo‐peroxo intermediate (cy‐salen)Mo(VI)(O)(η²‐O₂) (5); 4) theO‐transfer reaction of PMe₃with oxo‐peroxo species5at the oxo‐group, rather than the peroxo unit leading, after OPMe₃dissociation, to a monoperoxo species, (cy‐salen)Mo(IV)(η²‐O₂) (7); and 5) regeneration of the dioxo complex (cy‐salen)Mo(VI)O₂(1) from the monoperoxo triplet³7or singlet¹7by a concerted, asynchronous electronic isomerization. An alternative pathway for recycling of the oxo‐peroxo species5to the dioxo‐Mo1via a bimetallic peroxo complex LMo(O)‐O−O‐Mo(O)L8is determined to be energetically viable, but is unlikely to be competitive with the primary pathway for aerobic phosphine oxidation catalyzed by1.