One of these compounds mediates the addition of a silyl enol ether to a carbonyl in the Mukaiyama aldol reaction. For 10 points each:
[10m] Name these compounds, which can render carbonyl carbons susceptible to nucleophiles without protonating the oxygen. In another reaction, one of these compounds mediates addition of an acyl chloride to a benzene ring.
ANSWER: Lewis acids [prompt on acids] (The second reaction is the Friedel-Crafts acylation.)
[10e] Lewis acid catalysts with this property can be employed to render the Diels-Alder reaction asymmetric. “Centers” named for this property are carbons bonded to 4 different groups.
ANSWER: chirality [accept chiral centers]
[10h] Lanthanide salts of this functional group can be used as water-stable Lewis acid catalysts. This functional group is an excellent leaving group since the inductive effect gives its conjugate acid a pKa of -15.
ANSWER: triflates [or trifluoromethanesulfonates]
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