Alkynylthioimidazolium Salts: Efficient Reagents for the Synthesis of Alkynyl Sulfides by Electrophilic Thioalkynylation.

The efficient synthesis of a series of alkynylthioimidazolium salts through reaction of organozinc compounds with dibromo(imidazolium)sulfuranes is reported. Addition of Grignard reagents to these new species provided a highly modular, clean, and scalable access to a broad variety of alkynyl sulfides in good-to-excellent yields. The utility of this protocol was showcased by the preparation of alkynyl sulfides, which are particularly difficult to obtain or simply unavailable through the existing methodologies. In addition, the synthetic method was extended to the preparation of alkynyl selenides.

Dihalo(imidazolium)sulfuranes: A Versatile Platform for the Synthesis of New Electrophilic Group-Transfer Reagents.

The syntheses of imidazolium thiocyanates and imidazolium thioalkynes from dihalo(imidazolium) sulfuranes are reported and their reactivities as CN(+) and R-CC(+) synthons evaluated, respectively. The easy and scalable preparation of these electrophilic reagents, their operationally simple handling, broad substrate scope, and functional group tolerance clearly illustrate the potential of these species to become a reference for the direct electrophilic cyanation and alkynylation of organic substrates.

Favoring trienamine activation through unconjugated dienals: organocatalytic enantioselective remote functionalization of alkenes.

Unconjugated 2,5-dienals are more reactive substrates than the corresponding fully conjugated α,ß,γ,δ-unsaturated aldehydes towards organocatalytic activation through trienamine intermediates. This difference in reactivity has been demonstrated in the Diels-Alder reaction with nitroalkenes, a reaction that proceeds with clean ß,ε-selectivity to afford the final products in high yields and stereoselectivities, the related polyconjugated 2,4-dienals being completely unreactive.