The first iridium-catalyzed enantioselective vinylogous allylic alkylation of coumarins is presented. Using easily accessible linear allylic carbonates as the allylic electrophile, this reaction installs unfunctionalized allyl groups at the γ-position of 4-methylcoumarins in an exclusively branched-selective manner generally in high yields with an excellent level of enantioselectivity (up to 99 : 1 er).
Compared with the ever-growing list
of nonprochiral nucleophiles
in Ir-catalyzed asymmetric allylic substitution reactions, prochiral
nucleophiles are less studied. We present a new prochiral nucleophile,
namely, deconjugated butyrolactam, for Ir-catalyzed asymmetric allylic
alkylation (AAA). This reaction provides access to α-allyl deconjugated
butyrolactams with a moderate to good dr and an excellent er. This
is the first AAA reaction of deconjugated butyrolactams. Allyl transposition
through Cope rearrangement appears to proceed stereospecifically to
form γ-allyl conjugated butyrolactams.
Hydroxy-directed iridium-catalyzed enantioselective formal β‑C(sp2)–H allylic alkylation of kojic acid and structurally related α,β-unsaturated carbonyl compounds is developed. This reaction, catalyzed by an Ir(I)/(P,olefin) complex, utilizes the nucleophilic character of...
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