6113-61-7Relevant articles and documents
Enantioselective Synthesis of Quaternary Δ4- and Δ5-Dehydroprolines Based on a Two-Step Formal [3+2] Cycloaddition of α-Aryl and α-Alkyl Isocyano(thio)acetates with Vinyl Ketones
Odriozola, Amaiur,Oiarbide, Mikel,Palomo, Claudio
supporting information, p. 12758 - 12762 (2017/09/25)
A divergent synthesis of optically active quaternary Δ4- and Δ5-dehydro prolines is developed based on the first catalytic enantioselective conjugate addition of α-substituted isocyano(thio)acetates to vinyl ketones that is general for both α-aryl and α-alkyl isocyano(thio)acetates. The new tetrasubstituted C?N stereocenter is formed without the need of any metal salt due to a bifunctional tertiary amine/squaramide catalyst, featuring a bulky polyaryl sidearm and an unusually short squaramide diamide H???H interatomic distance in the solid state.
Mild and convenient N-formylation protocol in water-containing solvents
Aleiwi, Bilal A.,Mitachi, Katsuhiko,Kurosu, Michio
, p. 2077 - 2081 (2013/05/08)
We have realized that N-formylations of free amines of some drug leads can improve PK/PD property of parent molecules without decreasing their biological activities. In order to selectively formylate primary amines of polyfunctional molecules, we have sought a mild and convenient formylation reaction. In our screening of N-formylation of an α-amino acid, l-phenylalanine, none of formylation conditions reported to date yielded the desired HCO-l-Phe-OH with satisfactory yield. N-formylations of amino acids with HCO2H require a water-containing media and suppress polymerization reactions due to the competitive reactions among carboxylic acids. We found that N-formylations of α-amino acids could be achieved with a water-soluble peptide coupling additive, an Oxyma derivative, (2,2-dimethyl-1,3-dioxolan-4-yl)methyl-2-cyano-2- (hydroxyimino)acetate (2), EDCI, and NaHCO3 in water or a mixture of water and DMF system, yielding N-formylated α-amino acids with excellent yields. Moreover, these conditions could selectively formylate primary amines over secondary amines at a controlled temperature. A usefulness of these conditions was demonstrated by selective formylation of daptomycin antibiotic which contains three different amino groups.
Synthesis of chiral pentacyclo-undecane ligands and their use in the enantioselective alkylation of benzaldehyde with diethylzinc
Boyle, Grant A.,Govender, Thavendran,Kruger, Hendrik G.,Maguire, Glenn E.M.
, p. 2661 - 2666 (2007/10/03)
The synthesis of a new class chiral cage annulated bidentate ligands is reported. The ability of the chiral amino alcohols to catalyse the enantioselective addition of diethyl zinc to benzaldehyde was investigated. The cage annulated amino alcohols have C1 symmetry and showed poor to good enantioselectivity with high chemical yields. The system could be utilised as a versatile probe into the reaction mechanism. The synthesis of a new class of chiral pentacycloundecane cage annulated bidentate ligands is reported. This class of ligands can be used in many reactions that are catalysed by amino alcohol ligands. The ability of the chiral ligands to asymmetrically catalyse the reaction between diethylzinc and benzaldehyde was investigated. The cage annulated bidentate ligands have C1 symmetry and showed poor to good enantioselectivity with high yields compared to previous systems reported using other amino alcohol ligands. An important conclusion from the results is that both ligands should be involved in the mechanism as the bidentate ligands gives much improved enantioselectivity when compared with a single chiral source molecule. This system could be utilised as a versatile probe for examining the reaction mechanism.