A simple method has been developed for synthesis of γ-halo-enones. The approach employs a sequence involving initial indium-mediated allenylation reactions of phenacyl halides with propargyl bromide. This process is followed by acid-promoted rearrangement reactions of the formed homoallenic halohydrins. The new method can be incorporated into routes for the efficient synthesis of various five-membered
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.
Indium-mediated allylation/propargylation of α-diazoketones: a facile synthesis of 1-bromo-2-alkyl- or 2-arylpent-4-en-2-ols
作者:J.S. Yadav、B.V. Subba Reddy、P. Vishnumurthy、Swapan Kr. Biswas
DOI:10.1016/j.tetlet.2007.07.136
日期:2007.9
alpha-Diazoketones undergo smooth allylation with successive bromide insertion with allylindium bromide generated in situ from allyl bromide and indium metal to produce 1-bromo-2-alkyl- or 2-arylpent-4-en-2-ols in high yields. Addition of propargylindium bromide produces 1-bromo-2-alkyl-or 2-arylpent-4-yn-2-ols under similar conditions. (c) 2007 Published by Elsevier Ltd.