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The Sonogashira cross-coupling of 4,6-dichloro-2-pyrone with terminal acetylenes proceeds in good yields and high regioselectivity for the 6-position; dibenzylidene acetone (dba) type ligands play a non-innocent role in reactions mediated by Pd(dba)2/PPh3; theoretical studies indicate that C-6 oxidative addition is favoured both kinetically and thermodynamically.
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Fairlamb et al. (2006) studied this question.
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