| Abstract
| - The regioselectivity in the Pd(0)-catalyzed coupling−cyclization of 2-(2‘,3‘-allenyl)malonates withorganic halides is determined by the steric and electronic effects of both substrates. By deliberatecontrol of the reaction conditions, the regioselectivity of this reaction can be tuned. With conditionsA and B, the reaction afforded vinylic cyclopropane derivatives, while with conditions C and D, thereaction afforded cyclopentene derivatives in a highly selective manner. Under similar conditions,1-alkenyl halides tend to form more three-membered cyclic products. The increased steric hindranceat the 2‘-positon of the allene moiety and aryl halides favors the formation of five-membered cyclicproducts. The regioselectivity of the reaction may be explained by the comparison of the relativestabilities of syn- and anti-type π-allyl palladium intermediates.
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