α-Thiocarbonyl-stabilized Triphenylphosphonium Ylides: Preparation, Structure, and Alkylation Reactions

New Thiocarbonyl Ylides derived from 3,3-Dichloro-2,2,4,4-tetramethylcyclobutanethione; Generation and reactions

The reaction of 3,3-dichloro-2,2,4,4-tetramethylcyclobutanethione (1) with diazo compounds yielded spirocyclic 2,5-dihydro-1,3,4-thiadiazoles 3, which decomposed at ca. 45°C to give the corresponding thiocarbonyl ylide of type 4. In the absence of trapping agents, these thiocarbonyl ylides underwent a 1,3-dipolar electrocyclization to yield spirocyclic thiiranes 5. On the other hand, the thioca...

Carbenes stabilized by ylides: pushing the limits.

Selenophen - 2 - yl - substituted thiocarbonyl ylides – at the borderline of dipolar and biradical reactivity

The reactions of aryl (selenophen-2-yl) thioketones with CH2N2 occur with spontaneous elimination of N2, even at low temperature (-65°), to give regioselectively sterically crowded 4,4,5,5tetrasubstituted 1,3-dithiolanes and/or a novel type of twelve-membered dithia-diselena heterocycles as dimers of the transient thiocarbonyl S-methanides. The ratio of these products depends on the type of sub...

Enantioselective Decarboxylative Alkylation Reactions: Catalyst

α-Quaternary ketones are accessed through novel enantioselective alkylations of allyl and propargyl electrophiles by unstabilized prochiral enolate nucleophiles in the presence of palladium complexes with various phosphinooxazoline (PHOX) ligands. Excellent yields and high enantiomeric excesses are obtained from three classes of enolate precursors: enol carbonates, enol silanes, and racemic β-k...

Asymmetric 1,3-dipolar cycloadditons of stabilized azomethine ylides with nitroalkenes.

This review highlights the biological importance of many polysubstituted nitro-prolines and -pyrrolidines. Their preparation using asymmetric 1,3-dipolar cycloadditions of azomethine ylides with nitroalkenes using diastereoselective and enantioselective strategies is described remarking the scope and main features of each one.