Group 16 atoms, nucleophilic substitution recent studies

Metal-catalyzed substitution reactions involving propargylic derivatives have not been studied in much detail until recently [311, 312]. In this context, the ability shown by transition-metal allenylidenes to undergo nucleophilic additions at the Cy atom of the cumulenic chain has allowed the development of efficient catalytic processes for the direct substitution of the hydroxyl group in propargylic alcohols [313]. These transformations represent an appealing alternative to the well-known and extensively investigated Nicholas reaction, in which stoichiometric amounts of [Co2(CO)g] are employed [314-317]. 

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