Iodotrimethylsilane-Promoted Conjugate Addition of Organocopper Reagents, DDQ oxidation of Arylpropenes and Synthesis of 2-Arylcoumarans
Doctoral thesis, 1998

This thesis is divided into three parts: conjugate additions of organocopper reagents, DDQ oxidations of arylpropenes, and synthesis and steric assignment of 2-arylcoumarans. The iodotrimethylsilane(TMSI)-promoted conjugate addition of alkylcopper and copper acetylides to certain a,b-unsaturated carbonyl compounds is investigated. The RCu(LiI)-TMSI system is used in 1,4-additions to the optically active enoyl-amides of O-trityl-prolinol. Although the yields of 1,4-adducts were high (90-96%) the diastereoselectivities were only moderate (41-58%). Copper acetylides together with TMSI and LiI are an excellent reagent for 1,4-addition to certain a,.beta.-unsaturated carbonyl compounds. Aldehydes, b-alkoxy enones and a,.beta.-unsaturated ketones with a fixed or preferred s-trans conformation gave yields of the 1,4-adduct in the range of 67-98%. The presence of LiI is required to maintain the high yields. Several Cu(I) salts were studied for generation of the copper acetylides and the best results in the subsequent 1,4-addition were obtained with CuI. A survey of different halosilanes was made and the most efficient additive was TMSI. THF was found to be the best solvent for conjugate additions of alkyl copper and copper acetylides. A method for the synthesis of cinnamaldehydes by DDQ oxidation of 1-arylpropenes and 3-arylpropenes was developed. The nature of the substituents on the aromatic ring has significant importance for the formation of aldehydes. Electron-donating substituents such as methoxy groups at the aromatic ring promoted the formation of aldehydes (yields ? 80%). The formation of intermediate mono- and bis(3-aryl-2-propenyl) ethers of 2,3-dichloro-5,6-dicyanohydroquinone (DDHQ) was studied by 1H NMR spectroscopy. The 1-arylpropenes gave DDHQ ether intermediates faster than did the 3-arylpropenes. DDQ oxidation of 3-(3,4-dimethoxyphenyl)-1-propene in the presence of methanol gave methyl (E)-3-(3,4-dimethoxyphenyl)-propenoate in 55% yield. DDQ oxidation of 1- or 3-(3,4-dimethoxyphenyl)-1-propene in the presence of acetic acid gives an acylal in high yield [the diacetate of (E)-3-(3,4-dimethoxyphenyl)-2-propene-1,1-diol]. The cis and trans forms of 2-(3,4-dimethoxyphenyl)-3-hydroxymethyl-7-methoxy-2,3-dihydrobenzo[b]fura n were synthesized. These isomers provide a basis for the steric assignment of 2-arylcoumarans by 1H NMR spectral comparisons. Neolignans of the 2-arylcoumaran type reported in the literature were assigned and reassigned.







copper acetylides








conjugate addition


Tommy Iliefski

Department of Organic Chemistry

Subject Categories

Chemical Sciences



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 1389

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