A photoreaction between benzoyl compounds, such as benzoylformate derivatives, and 2-(p-anisyl)-1,3-dimethylbenzimidazoline in the presence of allyl bromide was found to give various allylated alcohols. In the reaction of benzoylformates, α-hydroxy ester enolates, for which the negative charge occurs on the carbonyl carbon of benzoyl (umpolung reactivity), are proposed to be generated as intermediates
Silver-Catalyzed Allenylation and Enantioselective Propargylation Reactions of Ketones
作者:Benjamin L. Kohn、Naoko Ichiishi、Elizabeth R. Jarvo
DOI:10.1002/anie.201206971
日期:2013.4.15
lining: Certain silver complexes are capable of selective catalysis of either allenylation or asymmetric propargylationreactions of ketones. Ligand‐free conditions lead to allenyl alcohols as the major product, whereas ligation with Walphos‐8 gives enantioenriched homopropargyl alcohols. This method can be applied to reactions of prochiral diarylketones to provide optically enriched tertiary diaryl alcohols
Asymmetric Propargylation of Ketones Using Allenylboronates Catalyzed by Chiral Biphenols
作者:David S. Barnett、Scott E. Schaus
DOI:10.1021/ol201535b
日期:2011.8.5
Chiralbiphenolscatalyze the enantioselective asymmetric propargylation of ketones using allenylboronates. The reaction uses 10 mol % of 3,3′-Br2-BINOL as the catalyst and allenyldioxoborolane as the nucleophile, in the absence of solvent, and under microwave irradiation to afford the homopropargylic alcohol. The reaction products are obtained in good yields (60–98%) and high enantiomeric ratios (3:1–99:1)
Zinc amide catalyzed, regioselective allenylation and propargylation of ketones with allenyl boronate is reported. Tertiary allenyl and homopropargyl alcohols were obtained, respectively, in high selectivities, from the same starting materials, simply by changing the reaction conditions. The substrate scope was wide. Mechanistic studies suggest that the reactions are controlled under kinetic and thermodynamic conditions.