Propargylation reactions

Metal-mediated carbonyl allylation, allenylation, and propargylation of optically pure azetidine-2,3-diones were investigated in aqueous environments.208 Different metal promoters showed varied regioselec-tivities on the product formation during allenylation/propargylation reactions of the kcto-fi-lactams. The stereochemistry of the new C3-substituted C3-hydroxy quaternary center was controlled by placing a chiral substituent at C4. The process led to a convenient entry to densely functionalized hydroxy-ji-lactams (Eq. 8.82). 

Despite this seminal work, it has only been recently that these metallacumulenes have really emerged as useful catalyst precursors or catalyst intermediates in organic synthesis. In particular, significant advances have been made in the field of alkene metathesis and propargylation reactions using mainly ruthenium complexes. A survey of this chemistry is presented in the following section. 

Cu(OH)2-catalyzed propargylation reaction was found to proceed rapidly and was completed within 5 min, even using 10 mol% of the catalyst to afford the desired product quantitatively (Table 5, entry 2). A lower loading (5 mol%) was also effective (Table 5, entry 3). On the other hand, the Bi(OH)3-catalyzed allenylation reaction was completed within 1.5 h in the presence of 5 mol% of... 

Prenyl bromide affords better chemical yields and better enantioselectivities than allyl bromide (Table 6). The best result (99% yield, 90% (R) ee) is obtained when benzaldehyde is treated with prenyl bromide in the presence of (—)-cinchonidine. A similar enantioselective propargylation reaction of aldehydes with enantioselectivity up to 85% has been achieved in organic solvents by using stoichiometric amounts of (—)-cinchonidine as the chiral source (Table 7).190... 

Carbazoles, 9-phenyl-, lithiation, 56, 191 Carbazole, 9-propargyl-, reaction with TeCU, 58, 112... 

AUylation and propargylation reactions. In the presence of the (Ph3P)4Pd catalyst, indium(I) iodide form organoindium(III) reagents with allylic halides and propargylic mesylates that react with carbonyl compounds in various solvents. 

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