Grignard reagents propargyl

Fallis and coworkers reported the synthesis of a tricyclic ABC ring-system of pacli-taxel using the three-component assembly of Grignard reagent, propargylic alcohol and aldehyde as a key step (Scheme 33) . ... 

The reaction of propargylic ethers proceeds through an addition-elimination pathway, which docs not involve the coppcr(III) intermediate. The stereochemical outcome varies with the nature of the halogen component of the Grignard reagent of RMgX6Sc. If the halogen is chloride, overall syn selectivity is obtained however, anti substitution results in the case of iodide. 

Cleavage of propargyl ethers by Grignard reagents 12-2 Rearrangement of alkynes... 

An one-pot reaction of propargyl alcohols 77 with Grignard reagents followed by treatment with electrophiles producing polysubstituted furans has been described <00TL17>. 

Among the more exotic cydopropylallenes, the polycyclic hydrocarbons 148 (n= 2, 3) may be cited, which are available by coupling the Grignard reagents 147 with propargyl bromide (116) in the presence of various metal catalysts, Fe(acac)3 leading to the highest yields (Scheme 5.21) [60]. 

Attempts to prepare the Grignard reagent from propargyl bromide under the usual conditions give rise to undesired reactions (compare [54]) ... 

Other kinds of propargylic-substituted products were prepared by this procedure. When Grignard reagents such as allylic and homoallylic magnesium bromides are used in place of lithium enolates as carbon-centered nucleophiles. 

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