third set composed of organic azides. Synthesized triazoles were then tested in vitro against B16 melanomacellline. Amongst them, compounds a1b1 (R1 = p-nitrophenyl, R2 = benzyl), a4b1 (R1 = naphthyl, R2 = benzyl) and a4b5 (R1 = naphthyl, R2 = (R/S)- dioxolane) showed the best activityagainst B16 melanomacells, with IC50 of 5.12, 3.89 and 6.60 muM respectively.
Biphenomycin B, a highly potent antibiotic against Gram-negative, β-lactam-resistant bacteria, which was previously isolated from culture filtrates of Streptomyces griseorubiginosusNO. 43708, has now been synthesised.
Improved synthetic methods for the preparation of three differently protected (2S,4R)-4-hydroxyornithines (10, 16, 24) have been developed which obviously can be used for the construction of the other stereoisomers. Formation of the corresponding α, β-didehydroamino acid derivatives (4, 15, 22) and their enantioselective hydrogenation are the characteristic steps of these syntheses.
Design and preparation of a novel prolinamide-based organocatalyst for the solvent-free asymmetric aldol reaction
作者:Rafaela de S. Martins、Mathias P. Pereira、Pedro P. de Castro、Fernanda I. Bombonato
DOI:10.1016/j.tet.2019.130855
日期:2020.1
proline-derived catalyst, providing access to the desired adducts in up to 95% yield, 1:19 syn/anti and 98% e.e. Moreover, even sterically bulky aldehydes and substituted cyclohexanones were well tolerated. DFT calculations and control experiments indicated that several hydrogen bonding interactions between the aldehyde and the enamine intermediate are responsible for the stereoselective chiral induction process
This article deal with the parallel synthesis of a 96 product-sized library using a polymer-based copper catalyst that we developed which can be easily separated from the products by simple filtration. This gave us the opportunity to use this catalyst in an automated chemical synthesis station (Chemspeed ASW-2000). Studies and results about the preparation of the catalyst, its use in different solvent systems, its recycling capabilities and its scope and limitations in the synthesis of this library will be addressed. The synthesis of the triazole library and the very good results obtained will finally be discussed.