The mechanism of the monoelectronic reduction of aromatic esters has been investigated. The unexpected synthetic utility of the toluate moiety in the deoxygenation of alcohols and the allylation of ketones is also reported. Finally, the use of aromatic esters as robust, though easily removable, protecting groups is depicted. (C) 2009 Elsevier Ltd. All rights reserved.
Regioselective Addition Reactions of Propargyl Bromides to Carbonyl Compounds with Gallium Catalyzed by Indium
作者:Phil Ho Lee、Hyun Kim、Kooyeon Lee
DOI:10.1002/adsc.200505046
日期:2005.7
propargyl bromides having substituents at the γ-position and gallium in the presence of 5 mol % of indium with aldehydes and ketones selectively produced homoallenyl alcohols in good to excellent yields. Treatment of organogallium reagents obtained from propargyl bromide or propargyl bromides having substituents at the α-position and gallium in the presence of 5 mol % of indium with carbonyl compounds selectively
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
Reductive addition of propargylic acetates to carbonyl compounds proceeded smoothly at room temperature by using SmI2 and a catalytic amount of Pd(PPh3)4 to give the corresponding acetylenic and/or allenic alcohols with appreciable selectivity. The method is useful especially for the preparation of tri- and tetrasubstituted allenic alcohols.
Zinc-Catalyzed Allenylations of Aldehydes and Ketones
作者:Daniel R. Fandrick、Jaideep Saha、Keith R. Fandrick、Sanjit Sanyal、Junichi Ogikubo、Heewon Lee、Frank Roschangar、Jinhua J. Song、Chris H. Senanayake
DOI:10.1021/ol202343c
日期:2011.10.21
The general zinc-catalyzed allenylation of aldehydes and ketones with an allenyl boronate Is presented. Preliminary mechanistic studies support a kinetically controlled process wherein, after a site-selective Ban exchange to generate a propargyl zinc intermediate, the addition to the electrophile effectively competes with propargyl-allenyl zinc equilibration. The utility of the methodology was demonstrated by application to a rhodium-catalyzed [4 + 2] cycloaddition.
Zinc Amide Catalyzed Regioselective Allenylation and Propargylation of Ketones with Allenyl Boronate
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.