Electrochemical Nickel-Catalyzed Synthesis of Unsymmetrical Diorganyl Selanes from Diaryl Diselanes and Aryl and Alkyl Iodides.

The synthesis of unsymmetrical diorganyl selanes was accomplished under electrochemical conditions in an undivided cell utilizing a magnesium cathode and a carbon anode made out of aryl and alkyl iodides and diselanes. This electrochemical cross-electrophile coupling (eXEC) was accomplished using a simple nickel catalyst formed in situ out of Ni(acac) and 2,2'-bipyridine in DMF at ambient temperatures. The reaction showed good functional group compatibility, and heteroaryl iodides, such as thiophene or pyridine derivatives, were well accepted.

Ligand-Controlled Diastereoselective Cobalt-Catalysed Hydroalkynylation of Terminal Alkynes to E- or Z-1,3-Enynes.

A diastereoselective hydroalkynylation of terminal alkynes to form the head-to-head dimerization products by two different cobalt-phosphine catalyst system is reported. The use of the bidentate ligand dppp and additional triphenylphosphine led to the selective formation of the (E)-1,3-enynes (E:Z>99:1) in good to excellent yields, while the tridentate ligand TriPhos led to the corresponding (Z)-1,3-enynes in moderate to good yields with excellent stereoselectivities (up to E:Z=1:99). Both pre-catalysts are easy to handle, because of their stability under atmospheric conditions.