Propargylic Substitution Reactions with Heteroatom-Centered Nucleophiles

Propargylic Substitution Reactions with Heteroatom-Centered Nucleophiles 

In the presence of a catalytic amount of methanethiolate-bridged diruthenium complex (la abbreviated as met-DIRUX), reactions of propargylic alcohols (2) with a variety of heteroatom-centered nucleophiles such as alcohols, thiols, amines, amides, and diphenylphosphine oxide gave the corresponding propargylic substituted 

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

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

The propargylic cations [Co2(/i,i/2,Tj3-RC2CR2)(CO)6]+ react as electrophiles with a variety of heteroatom- and carbon-centered nucleophiles to provide, following demetalation, propargylated products with complete regioselectivity. Complexation of the triple bond circumvents isomerization to allenic products. Reaction with asymmetrical ketones results in attack by the cation exclusively (>95%) at the more substituted a-carbon.72,74 (See Scheme 11.)... 

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