THESIS
2018
xiii, 240 pages : illustrations (some color) ; 30 cm
Abstract
The SmI
2-mediated reductive coupling reaction between non-conjugated aldehydes and
two 2-(dialkylamido)aryl 2,3-disubstituted α,β-unsaturated esters has been investigated. In
contrast to the corresponding 2- or 3-monosubstituted esters investigated in prior work, the
disubstituted substrate has not yet been used in this reaction despite offering the potential to
selectively forge three adjacent stereogenic centers in one step. Preliminary study on the
aldehyde scope and limitations of the reaction has been conducted; high diastereoselectivity
and good to high yields have been achieved for most of the investigated non-conjugated
aldehydes. The only observed systematic exceptions are the reactions of the 2-methyl-3-phenyl-substituted
acrylate with α-branched aldehydes that afforde...[
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The SmI
2-mediated reductive coupling reaction between non-conjugated aldehydes and
two 2-(dialkylamido)aryl 2,3-disubstituted α,β-unsaturated esters has been investigated. In
contrast to the corresponding 2- or 3-monosubstituted esters investigated in prior work, the
disubstituted substrate has not yet been used in this reaction despite offering the potential to
selectively forge three adjacent stereogenic centers in one step. Preliminary study on the
aldehyde scope and limitations of the reaction has been conducted; high diastereoselectivity
and good to high yields have been achieved for most of the investigated non-conjugated
aldehydes. The only observed systematic exceptions are the reactions of the 2-methyl-3-phenyl-substituted
acrylate with α-branched aldehydes that afforded drastically decreased selectivity
and in case of the highly sterically demanding pivaldehyde a very low yield. Exemplary use of
the chiral esters to form the enantiomerically enriched products is presented, although a
generally low and highly substrate-dependent enantioselectivity was observed. Finally, viability
of the reaction in the synthesis of natural products is indicated by utilizing it for a short total
synthesis of phaseolinic acid. Interpretation of the reaction results was attempted by proposing
a new mechanism which might explain the observed diastereoselectivity but will need further
experimental evidence for confirmation or correction.
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