= Solution
<amide ion> removes a methyl-side alpha <proton> of <pinacolone>. The C–H <electrons> form the <enolate> C=C bond as the <carbonyl> pi pair moves onto <oxygen>; <ammonia> is formed. The tert-butyl-side alpha <carbon> has no <hydrogen>, fixing the ordinary <enolate> regiochemistry.
The <carbon> end of D attacks the <acyl chloride> <carbonyl> <carbon>. Move the C=O pi pair onto <oxygen>, then collapse the <tetrahedral intermediate> with <chloride> departure. This <nucleophilic acyl substitution> gives $\mathrm{tCO{-}CH_2{-}COt}$ and constructs the bond between the original <enolate> methylene and the incoming <carbonyl>. \b[The observed product requires <carbon> acylation, rather than an O-acyl <enol> <ester>.] A further equivalent of D removes the much more acidic central <proton> of the new <1,3-diketone>, generating its extensively delocalized <enolate> and returning that second D equivalent to <pinacolone>. Aqueous <acid (chemistry)> workup protonates the product <enolate>; keto–<enol> equilibration gives the conjugated, internally stabilized by a <hydrogen bond> <enol> observed by <NMR>. The <acyl chloride> contributes its entire pivaloyl group; neither <tert-butyl group> is lost.
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