Copper-Catalyzed Enantioselective Synthesis of β-Boron β-Amino Esters
作者:Aurora López、Timothy B. Clark、Alejandro Parra、Mariola Tortosa
DOI:10.1021/acs.orglett.7b02784
日期:2017.12.1
In this report, the enantioselective, copper-catalyzed borylation of β-amidoacrylates is disclosed. A broad variety of biologically important α-aminoboronates has been prepared with consistently high levels of enantiocontrol using an inexpensive copper catalyst and a commercially available chiral ligand. The method can be applied to the synthesis of novel boron-containing dipeptides and hemiboronates
The reactions of Boc-β-amido- and β-amino acrylates, in which the CC possesses both nucleophilic and electrophilic sites, were investigated under acidic conditions. The trifluoroacetic-acid induced cyclization of the β-amido acrylates to the corresponding oxazolidin-2-ones involves a rarely seen nucleophilic attack of the carbamate carbonyl group. The cyclotrimerization of β-amino acrylates to N-substituted
The Construction of Polysubstituted Aromatic Core Derivatives<i>via</i>a Cycloaddition/Oxidative Aromatization Sequence from Quinone and β-Enamino Esters
AbstractAn unexpected strategy has been discovered for the construction of polysubstituted aromatic core derivatives from the reaction of quinones or N‐substituted maleimides with β‐enamino esters by a cycloaddition/oxidative aromatization sequence that provides products contrary to those delivered by the Nenitzescu reaction. The current method provides a highly favorable synthetic strategy for the efficient construction of important therapeutic agents containing polysubstituted aromatic core structures.magnified image
Catalyst-free one-pot, four-component approach for the synthesis of di- and tri-substituted<i>N</i>-sulfonyl formamidines
A straightforward one-pot, multicomponent approach was developed to synthesize di- and tri-substituted N-sulfonyl formamidines from sulfonyl chlorides, NaN3, ethyl propiolate, and primary/secondary amines under mild conditions without catalysts or additives. Structural analysis of the di-substituted sulfonyl formamidines indicated formation of the E-syn/anti isomeric form. Tri-substituted analogues
hydrolysis of the triester. These DHP derivatives are readily soluble in aqueous media buffered at pH 8.0 and the solutions give blue fluorescent signals with quantum yields of 7–23%. One of these compounds, bearing a p-methoxyphenyl N-substituted group, shows specific fluorescent quenching with the mercuricion (Hg2+). The fluorescent signal of the DHP derivative decays over a period of minutes to hours