An efficient, palladium-catalyzed, decarboxylative [4 + 2]-cycloaddition of 4-vinyl benzoxazinanones with carboxylic acids has been developed with the employment of P-chiral monophosphorus ligand BI-DIME, affording a series of structurally diverse 3,4-dihydroquinolin-2-ones bearing two contiguous stereogenic centers in moderate to good yields with good to excellent stereoselectivities.
A highly
efficient synthetic approach to unnatural chiral β-Ar,Ar′-α-amino
acid esters bearing two contiguous stereogenic centers has been developed.
The first enantioselective 1,6-conjugate addition of glycine Schiff
bases to para-quinone methides was achieved using
a Cu(CH3CN)4BF4/Ph-Foxap catalytic
system (1 mol %). The reaction proceeded smoothly to generate corresponding
products in high yields with excellent diastereoselectivities (up
to 99:1) and enantioselectivities (up to >99% ee). Subsequent reduction
delivered enantiopure unnatural amino alcohols, which were utilized
for the synthesis of novel chiral ligands.
A regiodivergent
organocatalytic enantioselective Michael addition/three-atom
ring expansion sequence of electron-withdrawing group activated cyclobutanones
with 2-nitrovinylindoles was developed. A series of azepino[1,2-a]indoles were obtained with exclusive regioselectivities
and high diastereo- and enantioselectivities (up to >20:1 dr, 96%
ee) with the application of the N1 nucleophilic site of the indole
nucleus. Meanwhile, various cyclohepta[b]indoles
could be accessed with high enantiopurity (up to 96% ee) through the
Michael addition/boron-trifluoride-etherate-promoted indole C3-attack
ring expansion process.
A highly enantioselective
Michael/lactonization cascade reaction
of 3-hydroxyoxindoles with 3-trifluoroethylidene oxindoles was developed.
The use of a cinchona-derived squaramide catalyst is essential in
achieving high diastereo- and enantioselectivities. This reaction
represents the first example of intramolecular amide C–N bond
cleavage and lactonization of 3-hydroxyoxindoles with 3-trifluoroethylidene
oxindoles, which provides an efficient and convenient approach to
diverse CF3-containing spirooxindole γ-lactones in
high yields and good to excellent diastereo- and enantioselectivities.
A variety of enantioenriched indole derivatives substituted in the benzene ring were synthesised via an organocatalytic asymmetric aza-Friedel-Crafts reaction of pyrazolinone ketimines with hydroxyindoles. This reaction was also applicabled to electron-rich phenols, yielding the desired products in high yields (up to 99%) and excellent stereo-selectivities (91-99% ee). Moreover, this method presents its potential in the synthesis of structurally novel indole-pyrazolinone conjugate derivatives.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.