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RESEARCH PRODUCT

Experimental and theoretical investigations for the tandem alkylation–isomerization reactions between unsaturated carboxylic acids and allyl halides

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Abstract—Alkylation of dienediolates from unsaturated carboxylic acids with allylic halides when followed by solventless thermaltreatment at 150 to 2008C afford rearranged products on a trend highly dependent on the acarbon substitution. Thus, 2,2-bisallylated acidswith H atoms at C-2 lead to its 1,3-shift, whereas 2-methyl-2,2-bisallylated acids lead to the corresponding Cope rearrangement product. Inthe latter case, this tandem allylation-Cope reaction lead, in a highly regio and diastereoselective way, to products not accessible from directalkylation. B3LYP/6-31G p energies for the compounds involved at these isomerizations are in reasonable agreement with the experiments,allowing to explain the formation of the more stable product under thermodynamic equilibrations.q 2003 Elsevier Ltd. All rights reserved. 1. IntroductionRegio and stereoselectivity studies on the reaction oflithium dienediolates with several electrophiles have beenreported in the last years 1–3 showing that, on reaction withprimary halides, the regioselectivity of the correspondingalkylation products strongly depends on the reactivity ofthe electrophile. Saturated alkyl halides show a higha-selectivity regardless of steric effects, whereas highlyreactive allyl and benzyl halides lead to poor a-selectivitieswhen steric effects become significant.