- Alkylation of alkenes: Ethylaluminum sesquichloride-mediated hydro-alkyl additions with alkyl chloroformates and di-tert-butylpyrocarbonate
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A general method for the hydro-alkyl addition to the nonactivated C=C double bond of alkenes using alkyl chloroformates (primary, secondary), 12, and di-tert-butylpyrocarbonate, 52, mediated by ethylaluminum sesquichloride (Et3Al2Cl3) has been developed. Reaction of 12 and 52, respectively, with Et3Al2Cl3 gives an alkyl cation which is added to the alkene; hydride transfer to the adduct carbenium ion or, if applicable, 1,2-H shift followed by hydride transfer from Et3Al2Cl3 to the rearranged adduct carbenium ion gives the saturated addition product. The reaction has been applied to 1-alkenes, 2-methyl-1-alkenes, internal double bonds, and to three cyclic alkenes. Special interest has been focused on alkylations of unsaturated fatty compounds, such as oleic acid (2), which are important renewable feedstocks. 2-Methylalkanes, 3-methylalkanes, 2,4-dimethylalkanes, 2,3-dimethylalkanes, 2,2,4-trimethylalkanes, cyclohexylalkanes, and carboxylic acids and esters with the respective branched alkyl chain have been synthesized with good to moderate yields.
- Biermann, Ursula,Metzger, Juergen O.
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p. 10319 - 10330
(2007/10/03)
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- Friedel-Crafts alkylation of alkenes: Ethylaluminum sesquichloride induced alkylations with alkyl chloroformates
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The formal addition of propane to nonactivated double bonds can be achieved with isopropyl chloroformate (2) in the presence of Et3Al2Cl3. Thus, a 1:1 mixture of 10-isopropyloctadecanoic acid (3) and the 9- regioisomer is formed from oleic acid (1). The reaction may also be carried out with 1-alkenes by the addition of triethylsilane as a hydride donor.
- Biermann, Ursula,Metzger, Juergen O.
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p. 3675 - 3677
(2007/10/03)
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- Synthesis and Absolute Configuration of 2-Hydroxy-12-methyl Tridecanoic Acid
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The synthesis of racemic 2-hydroxy-12-methyl tridecanoic acid is described.The absolute configuration of the two enantiomers has been determined by the method of Dale and Mosher. - Keywords: 2-Hydroxy-12-methyl Tridecanoic Acid, Absolute COnfiguration
- Balzer, Th.,Budzikiewicz, H.
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p. 1367 - 1368
(2007/10/02)
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