Being mono-aza analogues of sulfoxides and sulfones, sulfimides and sulfoximines, respectively, are important compounds in asymmetric synthesis, crop protection and medicinal chemistry. For their preparation various methods have been developed. In the search for the optimal synthetic approach for a given target compound, several parameters have to be considered which also include safety issues and availability of starting materials. In this tutorial review, we present an overview of sulfur imidation methods, classified by imidating agents and compounds with a related behaviour. The aim of this survey is to provide a practical ''tool box'' for the synthetic chemist by mapping the advantages and disadvantages associated with the use of these compounds.
Key learning points(1) Most imidating agents consist of the nitrogen atom to be transferred linked to a core fragment and a leaving group. (2) Sulfur imidation involves either the reaction between an electrophilic sulfonium salt and a nucleophilic nitrogen, or the addition of an electrophilic nitren(oid) species to a nucleophilic sulfur. (3) Toxicity and safety issues should be considered before choosing an imidation procedure. (4) Use of a catalytic amount of transition metal can considerably improve the imidation efficiency and allows stereoselective syntheses of sulfimides and sulfoximines.
1,4,2-Dioxazol-5-ones are five-membered heterocycles known to decarboxylate under thermal or photochemical conditions, thus yielding N-acyl nitrenes. Described herein is a light-induced ruthenium-catalyzed N-acyl nitrene transfer to sulfides and sulfoxides by decarboxylation of 1,4,2-dioxazol-5-ones at room temperature, thus providing direct access to N-acyl sulfimides and sulfoximines under mild reaction conditions. In addition, a one-pot sulfur imidation/oxidation sequence catalyzed by a single ruthenium complex is reported.
Dedicated to Dr.Philippe Bisseret on the occasion of his retirement acid fluorides ·C À Ffunctionalization ·cross-coupling · decarbonylation ·transition-metal catalysis Abstract: Several recent reports outlined the singular reactivity of acid fluorides as excellent electrophiles in transition-metal catalysis.These species undergo oxidative addition of the metal into the CÀFbond;then, retention or release of the CO moiety can occur and be controlled by tuning the catalytic system and the reaction parameters.A cid fluorides,w hichc an be derived from carboxylic acids,s how good stability and high reactivity in aw ide range of possible functionalizations with nucleophiles.T heir use provides an interesting alternative to that of the parent carboxylic acid derivatives (acid chlorides,e sters, amides,acids,o raldehydes).
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