Rhenium allenes

These -propargyl rhenium complexes undergo kinetic addition of nucleophiles at the central C atom to produce rhenacyclobutenes. The nucleophiles range from PR3 to malonate, acetylides, pyridines, and water. The derivatives of the addition of pyridines, however, are unstable and undergo further rearrangements to allene or acetylene complexes. Protonation of the metaUacyclobutenes produces u -allyl complexes. 

Yudha, S., Kuninobu, Y, Takai, K. (2008). Rhenium-catalyzed synthesis of stereodefined cyclopentenes from b-ketoesters and aliphatic allenes. Angewandte Chemie International Edition, 47, 9318-9321. 

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