We report the development of a stereoselective
method for the allylation
of ketones utilizing N-substituted allyl equivalents
generated from a chiral allenamide. By choice of the appropriate ligand
for the Cu-catalyst, high linear selectivity can be obtained with
good diastereocontrol. This methodology allows access to chiral γ-hydroxyaldehyde
equivalents that were applied in the synthesis of chiral γ-lactones
and 2,5-disubstitued tetrahydrofurans.
Herein, we report
the development of a catalytic enantioselective
addition of N-substituted allyl equivalents to ketone
electrophiles through use of Cu-catalyzed reductive coupling to access
important chiral 1,2-aminoalcohol synthons in high levels of regio-,
diastereo-, and enantioselectivity. Factors affecting enantioinduction
are discussed including the identification of a reversible ketone
allylation step that has not been previously reported in Cu-catalyzed
reductive coupling.
We report the development of a stereoselective method
for the allylation
of ketones utilizing N-substituted allyl equivalents generated from
a chiral allenamide. By employing N-heterocyclic carbenes as ligands
for the Cu catalyst, good branched selectivity can be obtained with
high diastereocontrol. This methodology allows access to a catalytically
generated, polarity-reversed (umpolung) allyl nucleophile to enable
the preparation of chiral 1,2-aminoalcohol synthons containing a dissonant
functional group relationship.
determined with each set of samples. A check standard (6 µg/L) was analyzed after every tenth sample.Callinan et al | http://dx.
Location
1-systems with substantial allochthonous contribution, 2-systems in which some THMFP samples exceeded detector, DOC-dissolved organic carbon, THMFP-trihalomethane formation potentialInset numbers represent percent increase relative to spring minimum.Callinan et al | http://dx.
Chiral γ-lactones are prevalent
organic architectures found
in a large array of natural products. In this work, we disclose the
development of a modified catalytic system utilizing a commercially
available Cu-phosphite catalyst for the diastereoselective reductive
coupling of chiral allenamides and ketones to afford chiral γ-lactone
precursors in 80:20 to 99:1 dr.
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