title: Indium-mediated beta-allylation, beta-propargylation, and beta-allenylation onto alpha,beta-unsaturated ketones: reactions of in-situ-generated 3-tert-butyldimethylsilyloxyalk-2-enylsulfonium salts with in-situ-generated organoindium reagents.
abstract: 3-tert-Butyldimethylsilyloxyalk-2-enylsulfonium salts, generated in situ from the reaction of alpha,beta-enones with dimethyl sulfide in the presence of TBSOTf, underwent a novel nucleophilic substitution with allylindiums to give silyl enol ethers of delta,epsilon-alkenyl ketones in good yields, which correspond to formal Michael addition products. In a similar manner, 1,4-propargylation of propargylindiums onto the sulfonium salts produced the corresponding silyl enol ethers of delta,epsilon-alkynyl ketones in good yields. Organoindium reagents derived from gamma-substituted propargyl bromide and indium afforded the corresponding silyl enol ethers of beta-allenyl ketones in good yields. The reaction proceeds via an addition-substitution mechanism involving the formation of allylic sulfonium salts. The presence of the intermediate sulfonium salt was confirmed by observation of the low-temperature (1)H NMR spectra.
authors.affiliation: Department of Chemistry, Kangwon National University, Chunchon 200-701, Republic of Korea.
authors.forename: Kooyeon
authors.initials: K
authors.lastname: Lee
authors.forename: Hyunseok
authors.initials: H
authors.lastname: Kim
authors.forename: Tomoya
authors.initials: T
authors.lastname: Miura
authors.forename: Koichi
authors.initials: K
authors.lastname: Kiyota
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kusama
authors.forename: Sunggak
authors.initials: S
authors.lastname: Kim
authors.forename: Nobuharu
authors.initials: N
authors.lastname: Iwasawa
authors.forename: Phil Ho
authors.initials: PH
authors.lastname: Lee