Thiadiynes, cyclic

Particularly useful in cyclic dialkyne chemistry is sulfide as a nucleophile. This is due to a discovery made by Regen and co-workers, who found that the yield of dialkyl sulfides is strongly enhanced when the sulfide reagent is first adsorbed onto AI2O3 thus, the substitution reaction takes place on the surface of the aluminum oxide. As the preparation of cyclic sulfides from dibromides is a stepwise process, these conditions were expected to increase the yield of cyclic sulfides dramatically as one end of the chain is immobilized after displacement of the first bromine [14]. Nicolaou first used this principle in the preparation of a series of cyclic thiadiynes [Eq. (6)] [15]. The cyclic thiadiynes prepared in this way are very useful as they can be converted to cyclic enediyne systems via the Ramberg-Backlund ring-contraction reaction (see below). 

Gleiter R, Classen J, Rausch B J, Oeser T, Rominger F (2002) Interaction of cyclic thiadiynes with CpCo(COD) - selectivity and reactivity. J OrganOTna Chem 641 3... 

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See also in sourсe #XX -- [ ]

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