Daniel L. Priebbenow

Copper-catalyzed oxidative cross-coupling of sulfoximines and alkynes

Until recently, the cross-coupling of two electron-rich nucleophilic substrates presented a significant challenge for synthetic organic chemists. In the past decade, however, several breakthroughs have been reported for such processes, such as employing transition-metal catalysts to facilitate the formation of either a new C C or C N bond between two nucleophiles. Realizing that this approach could also open access to N-alkynylated sulfoximines (2), which represent an essentially unexplored substrate class, we considered oxidative cross-coupling methods for the construction of the respective C N bonds (Scheme 1).

Copper-Catalyzed Oxidative Decarboxylative Couplings of Sulfoximines and Aryl Propiolic Acids

A method has been developed for the preparation of N-alkynylated sulfoximines involving the copper-catalyzed decarboxylative coupling of sulfoximines with aryl propiolic acids. A range of substituents on both the sulfoximidoyl moiety and the aryl group of the propiolic acid were compatible with this reaction process to afford a series of sulfoximidoyl-functionalized alkynes.

Acylsilanes: valuable organosilicon reagents in organic synthesis

Acylsilanes are a fascinating class of compounds that display a number of distinctive chemical and physical properties. The unique reactivity pattern of the acylsilane functional group [R-C(O)Si] makes them an increasingly attractive moiety in modern organic synthesis, and as such, they have been utilised in a diverse range of transformations. This review provides an overview of the recent advances in the synthesis and application of acylsilanes in organic chemistry, with a particular focus on the progress made in the last two decades.

N-Arylations of Sulfoximines with 2-Arylpyridines by Copper-Mediated Dual N–H/C–H Activation

A high-yielding method providing rapid access to new N-arylated sulfoximines has been developed. A stoichiometric amount of copper facilitates the C-H activation of 2-arylpyridines which then undergo oxidative C-N cross-couplings with various sulfoximine derivatives.

Recent advances in the Willgerodt–Kindler reaction

The Willgerodt-Kindler reaction has, in recent years, received limited attention and application in synthetic organic chemistry. With the advent of new technology such as microwave-assisted heating, several new, high-yielding, practical, and more environmentally friendly reaction protocols have been developed. This review aims to once again draw attention to this relatively underutilised process by highlighting the recent developments in the Willgerodt-Kindler reaction in the synthesis of (thio)amides, carboxylic acids, and heterocycles.

C-H activation of methyl arenes in the MnO2-mediated aroylation of N-chlorosulfoximines.

An investigation into the reactivity profile of N-halogenated sulfoximines has led to the development of a new method for the synthesis of N-aroylated sulfoximines. This protocol involves the manganese oxide promoted C-H activation of methyl arenes to form an aroyl intermediate which then reacts readily with N-chlorosulfoximines to form a series of valuable aroyl sulfoximine derivatives in high yields.

Acylsilanes in Rhodium(III)‐Catalyzed Directed Aromatic C–H Alkenylations and Siloxycarbene Reactions with CC Double Bonds

Acylsilanes are known to undergo a 1,2-silicon-to-oxygen migration under thermal or photochemical conditions to form siloxycarbenes. However, there are few reports regarding the application of siloxycarbenes in organic synthesis and surprisingly, their reaction with CC double or triple bonds remains virtually unexplored. To facilitate such a study, previously inaccessible aromatic acylsilanes containing an ortho-tethered CC double bond were identified as suitable substrates. To access these key intermediates, we developed a new synthetic method utilizing a rhodium-catalyzed oxidative Heck-type olefination involving the application of an acylsilane moiety as a directing group. When exposed to visible-light irradiation, the ortho-olefinated acylsilanes underwent a smooth intramolecular cyclization process to afford valuable indanone derivatives in quantitative yields. This result paves the way for the development of new transformations involving siloxycarbene intermediates.

Domino Heck-Aza-Michael Reactions: Efficient Access to 1-Substituted Tetrahydro-β-carbolines

A simple and efficient palladium-catalyzed domino reaction for the synthesis of a series of C1-substituted tetrahydro-beta-carbolines is described. This domino process involves a Heck reaction at the indole 2-position of a halogenated tryptamine precursor, followed by intramolecular aza-Michael addition.

A general approach to N-heterocyclic scaffolds using domino Heck-aza-Michael reactions.

Palladium-catalyzed domino Heck-aza-Michael reactions for the synthesis of a series of C1-substituted tetrahydro-β-carbolines, tetrahydroisoquinolines and isoindolines are described. The domino process involves the initial intermolecular Heck reaction of an aryl bromide with an electron deficient alkene, followed by an intramolecular aza-Michael reaction to form the new N-heterocycle in high yield.

Mild Copper‐Mediated Direct Oxidative Cross‐Coupling of 1,3,4‐Oxadiazoles with Polyfluoroarenes by Using Dioxygen as Oxidant

CH(3)CN and O(2) do the trick! A copper-mediated direct oxidative cross-coupling of 2-(het)aryl-1,3,4-oxadiazoles with polyhaloarenes under mild reaction conditions has been developed (see scheme). The process provides a concise access to biaryl structures containing polyhaloarenes, which are of interest in the fields of pharmaceuticals and functional materials. Acetonitrile and oxygen play crucial roles.