2577-90-4Relevant articles and documents
Propargyloxycarbonyl and propargyl groups for novel protection of amino, hydroxy, and carboxy functions
Kukase,Fukase,Kusumoto
, p. 1169 - 1170 (1999)
The propargyloxycarbonyl group readily introduced to both amino and hydroxy groups by using propargyl chloroformate is stable to neat TFA but is readily cleaved at ambient temperature by treatment with Co2(CO)8 and TFA in CH2Cl2 via formation of an alkyne-Co complex. The propargyl ester similarly serves as a good protecting group for carboxy functions.
Formation of lanthanide complexes with bipyridine-functionalized amide compounds and their unusually high amide reactivity
Araki,Kawaguchi,Kajikawa,Kaneko,Koshimizu
, p. 2729 - 2736 (1999)
The amide of 6-benzoylamino-6'-L-phenylalanyl-amino-2,2'-bipyridine (1a) was efficiently cleaved at 30°C to generate L-phenylalanine ester in methanol almost quantitatively. The reaction followed the Michaelis-Menten type via the 1:1 1a-Ln3+ complex. The half-life time of the scissile amide bond of the complex was as short as 2 min for the complex. The reactions depended on the structure of the substrates, which require 2,2'-bipyridine with two acylamino side chains at the 6,6'-positions and an amino group at the α-position of the scissile carbonyl. The less reactive 6-6'bis(benzoylamino)-2,2'-bipyridine with lanthanide cations formed 1:1 complexes. The formation constants were on the order of 103-105 cu dm/mole in methanol at 30°C. Coordination of the bipyridine nitrogens and the carbonyl oxygens was demonstrated in chloroform although coordination of the carbonyl oxygens was not seen in methanol.
Chiral N-hydroxybenzamides as potential catalysts for aerobic asymmetric oxidations
Capraro, Maria Grazia,Franchi, Paola,Lanzalunga, Osvaldo,Lapi, Andrea,Lucarini, Marco
, p. 6435 - 6443 (2014)
Chiral N-hydroxybenzamides (1H-3H) have been synthesized as precursors of chiral short-lived N-oxyl radicals 1?-3?. The latter species have been generated by oxidation of 1H-3H with Pb(OAc)4 or hydrogen abstraction from 1H-3H by the tert-butoxyl radical and characterized by UV-vis spectrophotometry and EPR spectroscopy. Through a kinetic study of the hydrogen atom transfer processes promoted by 1?-3? from three chiral benzylic substrates (1-phenylethylamine, 1-phenylethanol, and α-vinylbenzyl alcohol), a moderate chiral discrimination has been found, with selectivity factors 0.5 ≥ kH(S)/kH(R) ≥ 2.
Continuous flow heterogeneous catalytic reductive aminations under aqueous micellar conditions enabled by an oscillatory plug flow reactor
?tv?s, Sándor B.,Buchholcz, Balázs,Darvas, Ferenc,Kappe, C. Oliver,Novák, Zoltán,Sipos, Gellért,Wernik, Michaela
supporting information, p. 5625 - 5632 (2021/08/16)
Despite the fact that continuous flow processing exhibits well-established technical advances, aqueous micellar chemistry, a field that has proven extremely useful in shifting organic synthesis to sustainable water-based media, has mostly been explored under conventional batch-based conditions. This is particularly because of the fact that the reliable handling of slurries and suspensions in flow has been considered as a significant technical challenge. Herein, we demonstrate that the strategic application of an oscillatory plug flow reactor enables heterogeneous catalytic reductive aminations in aqueous micellar media enhancing mass transport and facilitating process simplicity, stability and scalability. The micellar flow process enabled a broad range of substrates, including amino acid derivatives, to be successfully transformed under reasonably mild conditions utilizing only very low amounts of Pd/C as a readily available heterogeneous catalyst. The preparative capabilities of the process along with the recyclability of the heterogenous catalyst and the aqueous reaction media were also demonstrated. This journal is
A General Stereocontrolled Synthesis of Opines through Asymmetric Pd-Catalyzed N-Allylation of Amino Acid Esters
Albat, Dominik,Neud?rfl, J?rg-Martin,Schmalz, Hans-Günther
supporting information, p. 2099 - 2102 (2021/07/22)
A stereo-divergent synthesis of natural and unnatural opines in stereochemically pure form is based on the direct palladium-catalyzed N-allylation of α-amino acid esters (up to 97 % ee or 99 : 1 d.r.) using methyl (E)-2-penten-4-yl carbonate in the presence of only 1 mol% of a catalyst, prepared in-situ from the C2-symmetric diphosphine iPr-MediPhos and [Pd(allyl)Cl]2. Selected target compounds (incl. a derivative of the drug enalapril) were efficiently obtained from the N-allylated intermediates by oxidative cleavage (ozonolysis) of the allylic C=C bond under temporary N-Boc-protection.