We have reported that the reaction of ethyl bromodifluoroacetate (1) with alkenyl iodides in the presence of copper powder gives ethyl alkenyldifluoroacetates. As an extension of this reaction, reaction of 1 with Michael acceptors in the presence of copper powder was examined and found to give 1,4-addition products selectively, unless the acceptor has a group stabilizing a radical intermediate, such
Reactions of ethyl bromodifluoroacetate in the presence of copper powder
作者:K. Sato、M. Omote、A. Ando、I. Kumadaki
DOI:10.1016/j.jfluchem.2003.11.023
日期:2004.4
We have examined the reaction of ethyl bromodifluoroacetate (1) in the presence of copper powder as a procedure for the synthesis of compounds containing a CF2 group. The complex formed in the above reaction reacted with vinyl or aryl iodides to give cross-coupling products, with Michael acceptors to give 1,4-addition products and with olefins to give radical addition products. The cross-coupling reaction
Reaction of ethyl bromodifluoroacetate with a variety of Michael acceptors was tremendously improved by the addition of TMEDA. Using this additive, 1,4-adducts were formed exclusively, and any 1,2-adducts or radical adducts were not obtained. THF or other low boiling solvents can be used as a solvent. This simplifies the work-up of the reaction effectively. (C) 2003 Elsevier Science B.V. All rights reserved.
Highly Improved Copper-Mediated Michael Addition of Ethyl Bromodifluoroacetate in the Presence of Protic Additive
yield with concomitant decreased use of reagent. Copper-mediated Michael addition of ethyl bromodifluoroacetate to Michael acceptors is accompanied by the formation of a substantial amount of byproducts. Elucidation of their structure hinted the cause of their formation, from which we discovered a highly improved and robust protocol by treatment with protic additives such as H2O and AcOH. This modification