A regio- and stereoselective thiocyanate addition to ynones is achieved using KSCN in AcOH at 70 °C. The reaction is extendable to ynals, ynesulfones, ynoic acids and ynoates. Adducts from ynones were readily transformed into thiazine-2-thione derivatives under slightly modified reaction conditions. In contrast, thiocyanated adducts from ynamides underwent an in situ decyanative amido cyclization towards isothiazolones. None of these events needed any transition metal or catalyst, attaining a high synthetic value.

Thes tereoselective E-iodosulfonylation of internala lkynes for synthesizing highly defined tetrasubstituted olefins using sodium phenyl sulfinate and iodine has been achieved.M osto ft he alkynes explored are non-symmetrical and the regioselection is under full control. Arylalkynes with various electron-withdrawing groups like keto,a ldehyde,e ster, amide,cyano,sulfone,bromo,c hloro and iodo on the other enda re identifieda ss uccessfulp recursors to yield the highly functionalized olefins.A lkynes directly tethered with heteroatoms are also found to be suitable substrates.Scheme 2. Iodosulfonylation of internal alkynes and ynoates.Scheme3.Iodosulfonylation different alkynes.Scheme4.Iodosulfonylation of haloalkynes.

A highly general palladium catalysed regioselective hydroalkynylation of ynamides for versatile enamide building blocks with an alkyne tether is achieved with an N-substitution dependent stereoselectivity switch under very mild reaction conditions.