An investigation into the poor activity of sulfides as catalysts for sulfonium-ylide-mediated methylene transfer to aldehydes has indicated that ylide formation is the problematic catalytic cycle step. Alkylation with traditional electrophiles does not proceed with sufficient efficiency to allow the sulfide to be used catalytically. Methyl triflate rapidly alkylates cyclic thiolanes under mild ...

Stabilised sulfur ylides are synthetically appealing compounds, which reactivity under Brønsted acid catalysis has been poorly explored. Herein, we report a new catalyst- and substrate- dependent chemodivergent reaction between stabilised salicylaldehydes, leading to the (suprising) formation of 2H-chromenes or dihydrobenzofurans products. Particular attention was set on unusual mechanisms invo...

Bestmann ylide [(triphenylphosphoranylidene)ketene] acts as a chemical linchpin that links nucleophilic entities, such as alcohols or amines, with carbonyl moieties to produce unsaturated esters and amides, respectively. In this work, the formation of α,β,γ,δ-unsaturated esters (dienoates) is achieved through the coupling of Bestmann ylide, an alcohol and an α,β-unsaturated aldehyde. Primary an...

Methionine, S-benzylcysteine and S-allylcysteine were converted into 2-diazo-3-oxo-4-phthalimidocarboxylic esters 8a-c in three steps. Upon rhodium-catalysed dediazoniation, two intramolecular carbenoid reactions competed, namely the formation of a cyclic sulfonium ylide and that of a six-ring carbonyl ylide. The S-methyl and S-benzyl ylides 12a and b could be isolated, while S-allyl ylide 12c ...

Rhodium-, copper- and iridium-catalyzed reactions of the (13)C-labelled diazo carbonyl substrates 18* and 19* were performed. Results obtained from copper- and iridium-catalyzed reactions of the (13)C-labelled α-diazo β-keto ester 19* indicate that either or both of these reactions do not proceed via a free oxonium ylide but instead follow a competing non-ylide route that delivers apparent [2,3...

Photochemical excitation of a diaryldiazomethane with an ortho-acetal both in solution and in crystals led to products that originate from the expected diarylcarbene and form an intramolecular oxonium ylide. While crystals strongly favored the formation of a benzocyclobutane by intramolecular hydrogen abstraction in the triplet carbene, reactions in benzene led exclusively to products that deri...

The use of ylides of P, N, As or S as ligands toward transition metals is still a very active research area in organometallic chemistry. This fact is mainly due to the nucleophilic character of the ylides and to their particular bonding properties and coordination modes. They can behave as monodentate or bidentate –chelate or bridging– species, they can be used as chiral auxiliary reagents, the...

A new ylide-initiated tandem cyclization reaction based on γ-dialkylation of allylic ylides has been realized, delivering a series of [3.3.0] oxa-bicyclic dienes in high yields with perfect diastereoselectivity.