Regioselective Addition Reactions of the Organoindium Reagents onto α,β-Unsaturated Ketones

Hyun Kim, Kooyeon Lee, Dong Seomoon, Sundae Kim, Heechul Kim, Hyunseok Kim, Miae Lee,Eunkyong Shim, Seokju Lee, Misook Kim, Mijeong Han, Kwanghyun Noh, and Madabhushi SridharDepartment of Chemistry, Kangwon National University, Chunchon 200-701, KoreaReceived May 18, 2004Regioselectivity on the reactions of α,β-enones with organoindium such as in situ generated allylindium andallenylindium was systematically studied in the presen ce of TMSCl as an additive. Treatment of 2-cyclohexen-1-one, carvone, 2-cyclohepten-1-one, and chalcone with allylindium reagent produced 1,4-addition products ingood yields, while 2-cyclopenten-1-one, 2-methyl-2-cyclopenten-1-one, 4,4-dimethylcyclohexen-1-one, 3-nonen-2-one, 4-hexen-3-one, and 4-phenyl-3-buten-2-one afforded 1,2-addition products. Indium reagentderived from indium and propargyl bromide in Grignard type gave addition products in good yields, underwhich the successive addition of α,β-enone and TMSCl were necessary. Although organoindium reagentderived from propargyl bromide produced propargylated compound in Grignard type except 2-cyclohepten-1-one, indium reagent obtained from 1-bromo-2-butyne having γ-methyl group gave allenylated product inBarbier type. Key Words : Regioselectivity, Conjugate addition, Allylindium, Allenylindium, Additive IntroductionAddition reaction of organometallic reagents with α,β-enones is one of the powerful methods for C-C bondformation. Michael addition reaction has been normallyachieved by using organocopper and organomagnesiumreagents in the presence of an additive such as copperhalides.