390766-89-9Relevant academic research and scientific papers
Asymmetric hydroalkylation of alkynes and allenes with imidazolidinone derivatives: α-alkenylation of α-amino acids
Bauer, Felix,Breit, Bernhard,Khosravi, Hormoz,Panahi, Farhad
, p. 7388 - 7392 (2021/06/09)
This work reports a new method for the synthesis of quaternary α-alkenyl substituted amino acids by the enantio- and diastereoselective addition of imidazolidinone derivatives to alkynes and allenes. Further hydrolysis of the imidazolidinone products under acidic conditions afforded biologically relevant amino acid derivatives. This method is geometry-selective (E-isomer), enantio- and diastereoselective, and products were obtained in good to excellent yields. The utility of this new methodology is proved by its operational simplicity and the successful accomplishment of gram-scale reactions. Experimental and computational studies suggest the key role of Li in terms of selectivity and support the proposed reaction mechanism.
Basicities and Nucleophilicities of Pyrrolidines and Imidazolidinones Used as Organocatalysts
An, Feng,Maji, Biplab,Min, Elizabeth,Ofial, Armin R.,Mayr, Herbert
supporting information, p. 1526 - 1547 (2020/02/04)
The Br?nsted basicities pKaH (i.e., pKa of the conjugate acids) of 32 pyrrolidines and imidazolidinones, commonly used in organocatalytic reactions, have been determined photometrically in acetonitrile solution using CH acids as indicators. Most investigated pyrrolidines have basicities in the range 16 aH aH aH 12.6) and the 2-imidazoliummethyl-substituted pyrrolidine A21 (pKaH 11.1) are outside the typical range for pyrrolidines with basicities comparable to those of imidazolidinones. Kinetics of the reactions of these 32 organocatalysts with benzhydrylium ions (Ar2CH+) and structurally related quinone methides, common reference electrophiles for quantifying nucleophilic reactivities, have been measured photometrically. Most reactions followed second-order kinetics, first order in amine and first order in electrophile. More complex kinetics were observed for the reactions of imidazolidinones and several pyrrolidines carrying bulky 2-substituents, due to reversibility of the initial attack of the amines at the electrophiles followed by rate-determining deprotonation of the intermediate ammonium ions. In the presence of 2,4,6-collidine or 2,6-di-tert-butyl-4-methyl-pyridine, the deprotonation of the initial adducts became faster, which allowed the rate of the attack of the amines at the electrophiles to be determined. The resulting second-order rate constants k2 followed the correlation log?k2(20 °C) = sN(N + E), where electrophiles are characterized by one parameter (E) and nucleophiles are characterized by the two solvent-dependent parameters N and sN. In this way, the organocatalysts A1-A32 were integrated in our comprehensive nucleophilicity scale, which compares n-, -, and σ-nucleophiles. The nucleophilic reactivities of the title compounds correlate only poorly with their Br?nsted basicities.
UNNATURAL AMINO ACIDS
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Paragraph 00185; 00211, (2018/07/05)
The present invention relates to a process for the preparation compounds of Formula (I): Formula (I) wherein X, Z, Q, Ar, R1, R2, R3 and R4 are each as defined herein. The present invention also relates to processes for the preparation of the compounds of quaternary amino acids and hydantions, to compound of Formula(I), to intermediate compounds of Formula (II), to quaternary amino acid compounds of Formula (III) and to hydantoin compounds of Formula (IV).
Aromatic Interactions in Organocatalyst Design: Augmenting Selectivity Reversal in Iminium Ion Activation
Holland, Mareike C.,Metternich, Jan Benedikt,Daniliuc, Constantin,Schweizer, W. Bernd,Gilmour, Ryan
supporting information, p. 10031 - 10038 (2015/07/07)
Substituting N-methylpyrrole for N-methyindole in secondary-amine-catalysed Friedel-Crafts reactions leads to a curious erosion of enantioselectivity. In extreme cases, this substrate dependence can lead to an inversion in the sense of enantioinduction. Indeed, these closely similar transformations require two structurally distinct catalysts to obtain comparable selectivities. Herein a focussed molecular editing study is disclosed to illuminate the structural features responsible for this disparity, and thus identify lead catalyst structures to further exploit this selectivity reversal. Key to effective catalyst re-engineering was delineating the non-covalent interactions that manifest themselves in conformation. Herein we disclose preliminary validation that intermolecular aromatic (CH-π and cation-π) interactions between the incipient iminium cation and the indole ring system is key to rationalising selectivity reversal. This is absent in the N-methylpyrrole alkylation, thus forming the basis of two competing enantio-induction pathways. A simple L-valine catalyst has been developed that significantly augments this interaction.
Enantioselective oxidation of thioanisole to metyl phenyl sulfoxide by chiral compounds bearing N-Cl bond
Ipek, Halil,Akdag, Akin
, p. 1285 - 1293 (2015/08/18)
Chiral sulfoxides are used in asymmetric synthesis and are present in various biologically active compounds. Asymmetric synthesis of the sulfoxides has been performed by chiral metal complexes and non-metals containing peroxide and oxide moieties. In this study, a new metal free method has been developed to oxidize thioanisole into methyl phenyl sulfoxide with easily accessible chiral compounds carrying N-Cl bond. For this purpose, chiral amine and amide bearing reagents were synthesized and chlorinated by using N-chlorosuccinimide. In oxidation reactions, chiral information has been transferred from N-chloramines to sulfides. With chlorinated chiral reagents, we observed enantioenriched sulfoxide formation. Although the observed results are promising, the best chiral amines are yet to be found. This is the first report on such a reaction, to the best of our knowledge.
Preparation and structures of 2-substituted 5-benzyl-3-methylimidazolidin- 4-one-derived iminium salts, reactive intermediates in organocatalytic transformations involving α,β-unsaturated aldehydes
Gro?elj, Uro?,Beck, Albert,Schweizer, W. Bernd,Seebach, Dieter
, p. 751 - 796 (2014/07/07)
Preparations of the title compounds, 5-7 (Scheme 1 and Table 1), of their ammonium salts, 9-11 (Scheme 2 and Table 2), and of the corresponding cinnamaldehyde-derived iminium salts 12-14 (Scheme 3 and Table 3) are reported. The X-ray crystal structures of 15 cinnamyliminium PF6 salts have been determined (Table 4). Selected 1H-NMR data (Table 5) of the ammonium and iminium salts are discussed, and structures in solution are compared with those in the solid state. Copyright
Transfer of 1-alkenyl groups between secondary amines. Relative stability and reactivity of enamines from popular organocatalysts
Carneros, Hector,Sanchez, Dani,Vilarrasa, Jaume
, p. 2900 - 2903 (2014/06/23)
Enamines from 3-methylbutanal and several Pro- and Phe-derived secondary amines were prepared in DMSO-d6, CD3CN, and CDCl 3. For the first time, the relative thermodynamic stabilities of these and other enamines were compared, and rapid exchanges of 1-alkenyl groups were demonstrated. Competition experiments showed that the most favored enamines (without significant steric inhibition of resonance) react more rapidly with electrophiles.
Highly enantioselective access to cannabinoid-type tricyles by organocatalytic Diels-Alder reactions
Braese, Stefan,Volz, Nicole,Glaeser, Franziska,Nieger, Martin
, p. 1385 - 1392 (2012/11/07)
After prosperous domino reactions towards benzopyrans, the products were used as the starting material in Lewis acid catalyzed and organocatalytic Diels-Alder reactions to build up a tricyclic system. Herein, an asymmetric induction up to 96% enantiomeric excess was obtained by the use of imidazolidinone catalysts. This approach can be utilized to construct the tricyclic system in numerous natural products, in particular the scaffold of tetrahydrocannabinol (THC) being the most representative one. Compared with other published methods, condensation with a preexisting cyclohexane moiety in the precursor is needed to gain the heterogenic tricycle systems, whereas we present a novel strategy towards cannabinoid derivatives based on a flexible modular synthesis.
Preparation of the MacMillan imidazolidinones
Samulis, Leopold,Tomkinson, Nicholas C.O.
supporting information; experimental part, p. 4263 - 4267 (2011/06/26)
A general method for the preparation of the MacMillan imidazolidinones is described. Treatment of an α-amino amide with a carbonyl compound in refluxing chloroform in the presence of Yb(OTf)3 (1 mol %) provides convenient access to the corresponding imidazolidinones.
Isolation and X-ray structures of reactive intermediates of organocatalysis with diphenylprolinol ethers and with imidazolidinones a survey and comparison with computed structures and with 1-acyl-imidazolidinones: The 1,5-repulsion and the geminal-diaryl
Seebach, Dieter,Groselj, Uros,Badine, D. Michael,Schweizer, W. Bernd,Beck, Albert K.
body text, p. 1999 - 2034 (2009/02/08)
Reaction of 2-phenylacetaldehyde with the Me3Si ether of diphenyl-prolinol, with removal of H2O, gives a crystalline enamine (1). The HBF4 salts of the MePh2Si ether of diphenyl-prolinol and of 2-(tert-butyl)-3-
