Another one is formed in an unfavorable step in the Mannich reaction.
A naturally occurring anti-HIV chemical called Lancifodilactone G contains an unusually stable example of this functional group. One of these is produced as the penultimate step of a version of the Oxy-Cope rearrangement, and the reaction of that compound provides the driving force of the reaction. Another one is formed in an unfavorable step in the Mannich reaction. An ester is converted to one of these before reacting with a second ester in the first step of the Claisen condensation, and one of these reacts with the carbonyl of an aldehyde or ketone as a key intermediate in the aldol addition. For 10 points, name this functional group which can be formed by the deprotonation of a beta carbon and protonation of a carbonyl, a tautomer of an aldehyde of ketone.
A naturally occurring anti-HIV chemical called Lancifodilactone G contains an unusually stable example of this functional group.
{enolate} [prompt on {alcohol} or {alkene}, since {both} are {parts} of an {enol}]