The unique regioselectivity and reactivity of cobalt(III) in the direct cyclization of N‐nitrosoanilines with alkynes for the expedient synthesis of N‐substituted indoles is demonstrated. In the ...presence of a cobalt(III) catalyst, high regioselectivity was observed when using unsymmetrical meta‐substituted N‐nitrosoanilines. Moreover, internal alkynes bearing electron‐deficient groups, which are almost unreactive in the Cp*RhIII‐catalyzed system, display good reactivity in this transformation.
Cp* and Co.: The unique regioselectivity and reactivity of cobalt(III) in the direct cyclization of N‐nitrosoanilines with alkynes for the expedient synthesis of a variety of N‐substituted indoles is demonstrated. In the presence of a cobalt(III) catalyst, high regioselectivity was observed when using unsymmetrical meta‐substituted N‐nitrosoanilines. Cp*=C5Me5.
Because of the importance of nitrogen-containing compounds in chemistry and biology, organic chemists have long focused on the development of novel methodologies for their synthesis. For example, ...nitrogen-containing compounds show up within functional materials, as top-selling drugs, and as bioactive molecules. To synthesize these compounds in a green and sustainable way, researchers have focused on the direct functionalization of hydrocarbons via C–H or C–C bond cleavage. Although researchers have made significant progress in the direct functionalization of simple hydrocarbons, direct C–N bond formation via C–H or C–C bond cleavage remains challenging, in part because of the unstable character of some N-nucleophiles under oxidative conditions. The nitriles are versatile building blocks and precursors in organic synthesis. Recently, chemists have achieved the direct C–H cyanation with toxic cyanide salts in the presence of stoichiometric metal oxidants. In this Account, we describe recent progress made by our group in nitrile synthesis. C–H or C–C bond cleavage is a key process in our strategy, and azides or DMF serve as the nitrogen source. In these reactions, we successfully realized direct nitrile synthesis using a variety of hydrocarbon groups as nitrile precursors, including methyl, alkenyl, and alkynyl groups. We could carry out Csp3 –H functionalization on benzylic, allylic, and propargylic C–H bonds to produce diverse valuable synthetic nitriles. Mild oxidation of CC double-bonds and CC triple-bonds also produced nitriles. The incorporation of nitrogen within the carbon skeleton typically involved the participation of azide reagents. Although some mechanistic details remain unclear, studies of these nitrogenation reactions implicate the involvement of a cation or radical intermediate, and an oxidative rearrangement of azide intermediate produced the nitrile. We also explored environmentally friendly oxidants, such as molecular oxygen, to make our synthetic strategy more attractive. Our direct nitrile synthesis methodologies have potential applications in the synthesis of biologically active molecules and drug candidates.
Often used as a common solvent for chemical reations and utilized widely in industry as a reagent, N,N‐dimethylformamide (DMF) has played an important role in organic synthesis for a long time. ...Numerous highly useful articles and reviews discussing its utilizations have been published. With a focus on the performance of DMF as a multipurpose precursor for various units in numerous reactions, this Minireview summarizes recent developments in the employment of DMF in the fields of formylation, aminocarbonylation, amination, amidation, and cyanation, as well as its reaction with arynes.
All‐purpose reagent: In addition to being an effective polar solvent for chemical reactions, N,N‐dimethylformamide (DMF) can serve as the source for a variety of units, such as CHO, CHNMe2, C(O)NMe2, NMe2, and CN among others (see scheme). Recent developments in the employment of DMF as a reactant are reviewed.
A novel TEMPO-catalyzed aerobic oxygenation and nitrogenation of hydrocarbons via CC double-bond cleavage has been disclosed. The reaction employs molecular oxygen as the terminal oxidant and ...oxygen-atom source by metal-free catalysis under mild conditions. This method can be used for the preparation of industrially and pharmaceutically important N- and O-containing motifs, directly from simple and readily available hydrocarbons.
A novel and efficient copper-catalyzed azidation reaction of anilines via C–H activation has been developed. This method, in which the primary amine acts as a directing group by coordinating to the ...metal center, provides ortho azidation products regioselectively under mild conditions. This effective route for the synthesis of aryl azides is of great significance in view of the versatile reactivity of the azide products.
This paper describes the direct cyanation of indoles and benzofurans employing N,N-dimethylformamide (DMF) as both reagent and solvent. Isotopic labeling experiments indicated that both the N and the ...C of the cyano group derived from DMF. This transformation offers an alternative method for preparing aryl nitriles, though it is currently limited in scope to indoles and benzofurans.
For green and sustainable chemistry, molecular oxygen is considered as an ideal oxidant due to its natural, inexpensive, and environmentally friendly characteristics, and therefore offers attractive ...academic and industrial prospects. This critical review introduces the recent advances over the past 5 years in transition-metal catalyzed reactions using molecular oxygen as the oxidant. This review highlights the scope and limitations, as well as the mechanisms of these oxidation reactions (184 references).
A novel Cu-catalyzed oxidative amidation−diketonization reaction of terminal alkynes leading to α-ketoamides has been developed. This chemistry offers a valuable mechanistic insight into this novel ...Cu catalysis via a radical process. O2 not only participates as the ideal oxidant but also undergoes dioxygen activation under ambient conditions in this transformation.
