Propargylic substitution reactions

Thiolate-bridged diruthenium complexes such as Cp RuCl(p2-SR)2RuCp Cl catalyze the propargylic substitution reaction of propargylic alcohol derivatives with various carbon-centered nucleophiles [118-120]. Ketones [119] (Eq. 88), aromatic compounds [120] (Eq. 89), or alkenes thus selectively afford the corresponding propargylated products with C-C bond formation. An allenylidene intermediate is proposed in these reactions. They are detailed in the chapter Ruthenium Vinylidenes and Allenylidenes in Catalysis of this volume. 

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Propargylic substitution reaction is one of the most important routes to allenic compounds [1, 2], As shown in Scheme 3.1, replacement of a leaving group at the propargylic position with an incoming nucleophile via an SN2 pathway rearranges the C=C-C skeleton into a C=C=C moiety to give a propadienyl species. With certain... 

Scheme 39 Propargylic substitution reactions catalyzed by complex 105a...

Scheme 40 Proposed catalytic cycle for the Ru-catalyzed propargylic substitution reactions...

Scheme 41 Propargylic substitution reactions with enolizable ketones...

Fig. 21 Products obtained through propargylic substitution reactions with carbon-centred nucleophiles...

Propargylic Substitution Reactions with Heteroatom-Centered Nucleophiles... 

Scheme 7.5 Propargylic substitution reactions of propargylic alcohols with a variety of heteroatom-centered nucleophiles.

Diphenylphosphine oxide can be used as a phosphorus-centered nucleophile for propargylic substitution reactions, where its tautomer (diphenylphosphinous acid) is... 

Scheme 7.9 Propargylic substitution reaction with acetone as a carbon-centered nucleophile.

Scheme 7.10 Propargylic substitution reactions with unsymmetrical simple ketones.

Scheme 7.13 Catalytic activity toward propargylic substitution reactions and electronic properties of chalcogenolate-bridged...

Scheme 7.14 Proposed reaction pathway for the catalytic propargylic substitution reaction.

The best enantioselectivity (35% ee) was observed in the reaction of l-(l-naphthyl)-2-propyn-l-ol with acetone in the presence of a complex bearing a 1-naphthylethylthio-lato moiety as a chiral ligand. Although the enantioselectivity is not yet satisfactory, this was the first example of an enantioselective propargylic substitution reaction catalyzed by transition metal complexes [27]. It is noteworthy that the chiral thiolate-bridged ligands work to control the chiral environment around the diruthenium site. 

Scheme 7.19 The first example of enantioselective propargylic substitution reactions catalyzed by chiral thiolate-bridged diruthenium complexes.

Scheme 7.21 Enantioselective propargylic substitution reactions of various propargylic alcohols catalyzed by a chiral thiolate-bridged diruthenium complex.

After our discovery of the chalcogenolate-bridged diruthenium complex-catalyzed propargylic substitution reactions of propargylic alcohols with a variety of nucleophiles via allenylidene intermediates, as described in the previous sections, some... 

Some metal salts and Bronsted add were reported to work as catalysts for the propargylic substitution reactions, see ... 

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