Enabling iron catalyzed Doyle-Kirmse rearrangement reactions with in situ generated diazo compounds

Solvent-dependent, rhodium catalysed rearrangement reactions of sulfur ylides

Depending on the solvent used, benzyl sulfides undergo in the presence of a rhodium(ii) catalyst either [1,2]- or [2,3]-sigmatropic rearrangement.

Perfluoroalkyl Aziridines with Ruthenium Porphyrin Carbene Intermediates

A new and efficient synthesis of multifunctionalized perfluoroalkyl aziridines via a ruthenium-perfluoroalkylcarbene intermediate is described. With Ru( p-Cl-TPP)CO as the catalyst, in situ generated C _nF_{2 n+1}CHN₂ from C _nF_{2 n+1}CH₂NH₃Cl underwent a cascade of nitrone formation/1,3-diploar cycloaddition/rearrangement reactions with nitrosoarenes and alkynes to give a variety of multifunctionalized perfluoroalkyl aziridines in good to high yields and with moderate to high diastereoselectivity. The ruthenium-perfluoroalkylcarbene intermediates obtained through the stoichiometric reaction of ruthenium porphyrin and C _nF_{2 n+1}CHN₂ were spectroscopically characterized.

Highly Diastereo- and Enantioselective Synthesis of Nitrile-Substituted Cyclopropanes by Myoglobin-Mediated Carbene Transfer Catalysis

A chemobiocatalytic strategy for the highly stereoselective synthesis of nitrile-substituted cyclopropanes is reported. The present approach relies on an asymmetric olefin cyclopropanation reaction catalyzed by an engineered myoglobin in the presence of ex situ generated diazoacetonitrile within a compartmentalized reaction system. This method enabled the efficient transformation of a broad range of olefin substrates at a preparative scale with up to 99.9 % de and ee and up to 5600 turnovers. The enzymatic product could be further elaborated to afford a variety of functionalized chiral cyclopropanes. This work expands the range of synthetically valuable, abiotic transformations accessible through biocatalysis and paves the way to the practical and safe exploitation of diazoacetonitrile in biocatalytic carbene transfer reactions.

Cyanomethyl anion transfer reagents for diastereoselective Corey-Chaykovsky cyclopropanation reactions

A readily available and bench-stable cyanomethyl sulfonium salt was used in highly diastereoselective Corey-Chaykovsky cyclopropanation reactions of electron-poor olefins. This efficient method provides a rapid route to access densely functionalized cyclopropyl nitriles.

The Generation of Diazo Compounds in Continuous-Flow

Toxic, cancerogenic and explosive-these attributes are typically associated with diazo compounds. Nonetheless, diazo compounds are nowadays a highly demanded class of reagents for organic synthesis, yet the concerns with regards to safe and scalable transformations of these compounds are still exceptionally high. Lately, the research area of the continuous-flow synthesis of diazo compounds attracted significant interest and a whole variety of protocols for their "on-demand" preparation have been realized to date. This concept article focuses on the recent developments using continuous-flow technologies to access diazo compounds; thus minimizing risks and hazards when working with this particular class of compounds. In this article we discuss these concepts and highlight different pre-requisites to access and to perform downstream functionalization reaction.

Sulfur-Based Ylides in Transition-Metal-Catalysed Processes

Traditionally employed in the synthesis of small ring systems and rearrangement chemistry, sulfur-based ylides occupy a unique position in the toolbox of the synthetic organic chemist. In recent years a number of pioneering researchers have looked to expand the application of these unorthodox reagents through the use of transition metal catalysis. The strength and flexibility of such a combination have been shown to be of key importance in developing powerful novel methodologies. This chapter summarises recent developments in transition metal-catalysed sulfonium/sulfoxonium ylide reactions, as well as providing a historical perspective. In overviewing the successes in this area, the authors hope to encourage others into this growing field.

Iron-catalysed carbene-transfer reactions of diazo acetonitrile

Herein we report the flow synthesis of hazardous diazo acetonitrile to enable X–H insertion reactions with a readily available iron catalyst.