Unnatural α-amino ethyl esters from diethyl malonate or ethyl β-bromo-α-hydroxyiminocarboxylate
We have explored here the scope of the age-old diethyl malonate-based accesses to α-amino esters involving Knoevenagel condensations of diethyl malonate on aldehydes, reductions of the resulting alkylidenemalonates, the preparation of the corresponding α-hydroxyimino esters and their final reduction. This synthetic pathway turned out to be general although some unexpected limitations were encountered. The synthetic modifications of some of the intermediates - using Suzuki-Miyaura coupling or cycloadditions - before undertaking the oximation step - provided accesses to further α-amino esters. Moreover, other pathways to α-hydroxyimino esters were explored including an attempt to improve the cycloadditions between ethyl β-bromo-α-hydroxyiminocarboxylate and various alkylfuranes.
Coutant, Eloi P.,Hervin, Vincent,Gagnot, Glwadys,Ford, Candice,Baatallah, Racha,Janin, Yves L.
supporting information
p. 2853 - 2860
(2018/11/26)
Synthesis and activity evaluation of the cyclic dipeptides arylidene N-alkoxydiketopiperazines
A series of arylidene N-alkoxydiketopiperazines was designed and stereoselectively synthesized via oxime-ether formation and intramolecular acylation. Possible cyclization and acid-catalyzed rearrangement-fragmentation mechanisms were discussed. The crystal structure of the novel diketopiperazine further confirmed the rearrangement mechanism. Most compounds exhibited antitumor activity. Several compounds were more potent against caspase-3. Specifically, compounds 6e, 6g, and 6f inhibited caspase-3 at IC50values lying within the low micromolar range and demonstrated good selectivity. The binding modes of alkoxydiketopiperazines in the active center of caspase-3 were also discussed based on the molecular docking results.
Nano-K2CO3: Preparation, characterization and evaluation of reactive activities
A novel base, nano-K2CO3, was easily prepared by ultrafine wet milling. The surface properties and the reactive activities of nano-K2CO3 were characterized. It was found that such a base showed higher basicity than normal K2CO3 and could replace sodium (or potassium) alkoxide to carry out monoalkylation and oximation of active methylene compounds. The nano-K2CO3 could be regenarated and reused 10 times without loss of its reactive activity.
Stereoselective synthesis and rearrangement-fragmentation of arylidene N-alkoxydiketopiperazines
A stereoselective synthesis of arylidene N-alkoxydiketopiperazines via oxime-ether formation and intramolecular acylation is described, followed by an acid-catalysed rearrangement-fragmentation to give novel diketopiperazine hemiaminal derivatives with us
Liu, Shouxin,Mu, Yun,Han, Jianrong,Zhen, Xiaoli,Yang, Yihua,Tian, Xia,Whiting, Andrew
experimental part
p. 7476 - 7481
(2011/12/03)
Design, synthesis, and anti-tumor activity of (2-O-alkyloxime-3-phenyl)- propionyl-1-O-acetylbritannilactone esters
The extracts of Inula britannica have anti-inflammatory, anti-bacterial, anti-hepatitic, and anti-tumor activities. Various sesquiterpene lactones with cytotoxic properties including 1-O-acetylbritannilactone (1) have been isolated from this Chinese medic