scholarly journals Diastereoselective Ugi reaction of chiral 1,3-aminoalcohols derived from an organocatalytic Mannich reaction

2016 ◽  
Vol 12 ◽  
pp. 139-143 ◽  
Author(s):  
Samantha Caputo ◽  
Andrea Basso ◽  
Lisa Moni ◽  
Renata Riva ◽  
Valeria Rocca ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Multicomponent Reaction ◽  
Mannich Reaction ◽  
Ugi Reaction ◽  
Enantiomerically Pure ◽  
Stereogenic Centers

Enantiomerically pure β-aminoalcohols, produced through an organocatalytic Mannich reaction, were subjected to an Ugi multicomponent reaction under classical or Lewis acid-promoted conditions with diastereoselectivities ranging from moderate to good. This approach represents a step-economical path to enantiomerically pure, polyfunctionalized peptidomimetics endowed with three stereogenic centers, allowing the introduction of five diversity inputs.

Stereochemistry of epoxide carbonylation using bimetallic Lewis acid/metal carbonyl complexes

2004 ◽  
Vol 76 (3) ◽  
pp. 557-564 ◽  
Author(s):  
Y. D. Y. L. Getzler ◽  
Viswanath Mahadevan ◽  
E. B. Lobkovsky ◽  
G. W. Coates
Keyword(s):  
Lewis Acid ◽  
Kinetic Resolution ◽  
Metal Carbonyl ◽  
Carbonyl Complexes ◽  
Enantiomerically Pure ◽  
Metal Carbonyl Complexes ◽  
Pure Complex

The stereochemistry of epoxide carbonylation using bimetallic [Lewis acid]+[Co(CO)4]- complexes is reported. The achiral complex [(salph)Al(THF)2][Co(CO)4] stereospecifically carbonylates cis- and trans-2-butene oxide to the trans- and cis-β-lactones, respectively. Preliminary experiments regarding the carbonylative kinetic resolution of racemic trans-2-butene oxide using the enantiomerically pure complex [(R,R-salcy)Al(THF)2][Co(CO)4] are also reported.

A heavy metal- and oxidant-free, one-pot synthesis of pyridines and fused pyridines based on a Lewis acid-catalyzed multicomponent reaction

2014 ◽  
Vol 50 (82) ◽  
pp. 12270-12272 ◽  
Author(s):  
V. P. Alex Raja ◽  
Giammarco Tenti ◽  
Subbu Perumal ◽  
J. Carlos Menéndez
Keyword(s):  
Heavy Metal ◽  
Lewis Acid ◽  
Multicomponent Reaction ◽  
One Pot ◽  
One Pot Synthesis ◽  
Acid Catalyzed

Pyridines and fused pyridines are accessible by a combination of a Lewis acid-catalyzed multicomponent reaction and aromatization involving loss of a 2-furylmethyl chain.

Enantioselective Organocatalytic Construction of Carbocycles: The Nicolaou Synthesis of Biyouyanagin A

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Methyl Ether ◽  
Conjugate Addition ◽  
Unsaturated Aldehyde ◽  
Enantiomerically Pure ◽  
Intramolecular Alkylation ◽  
Stereogenic Centers ◽  
Chinese Academy Of Sciences ◽  
Academy Of Sciences ◽  
Polycyclic System ◽  
Selective Addition

One of the more powerful routes to enantiomerically-pure carbocycles is the desymmetrization of a prochiral ring. Karl Anker Jørgensen of Aarhus University has found (J. Am. Chem. Soc. 2007, 129, 441) that many cyclic β-ketoesters, including the vinylogous carbonate 1, can be homologated with 2 to the corresponding alkyne 3, in high ee. Sanzhong Luo of the Chinese Academy of Sciences, Beijing, and Jin-Pei Cheng, of the Chinese Academy of Sciences and Nankai University, have shown (J. Org. Chem. 2007, 72, 9350) that the catalyst 6 mediated the selective addition of 4-substituted cyclohexanones such as 4 to the nitroalkene 5, establishing three new stereogenic centers. Organocatalysts, alone or complexed with activating metals, have also been used to effect enantioselective ring construction. E. J. Corey of Harvard University has established (J. Am. Chem. Soc. 2007, 129, 12686) that the proline-derived complex 10 will mediate the 2 + 2 addition of a cyclic enol ether with an acrylate to give the cyclobutane 11. Further elaboration led to the cyclohexenone 12. Armando Córdova of Stockholm University has described (Tetrahedron Lett. 2007, 48, 5835) a novel route to cyclopentanones such as 16, via tandem conjugate addition/intramolecular alkylation. Professor Jørgensen has reported (Angew. Chem. Int. Ed . 2007, 46 , 9202) the double addition of 18 to the unsaturated aldehyde 17 to give 20. Earlier last year, Yujiro Hayashi of the Tokyo University of Science had shown (Angew. Chem. Int. Ed. 2007, 46, 4922) that the double addition of the inexpensive 21 to 5 could, depending on conditions, be directed selectively to 22, 23, or 24. As illustrated by the conversion of 8 to 13, organocatalysis can be used to effect the enantioselective construction of polycarbocyclic products. The initial ring prepared in enantiomerically-pure form by organocatalysis can also set the chirality of a polycyclic system. Professor Corey has reported (J. Am. Chem. Soc. 2007, 129, 10346) that Itsuno-Corey reduction of the prochiral diketone 25 led to the ketone 27. Cyclization followed by oxidation and reduction then delivered estrone methyl ether 28.

scholarly journals Tartaric Acid–Zinc Nitrate as an Efficient Brønsted Acid-Assisted Lewis Acid Catalyst for the Mannich Reaction

2018 ◽  
Vol 42 (9) ◽  
pp. 463-466 ◽  
Author(s):  
Hao Dong ◽  
Qing Liu ◽  
Yuanyu Tian ◽  
Yingyun Qiao
Keyword(s):  
Tartaric Acid ◽  
Lewis Acid ◽  
Mannich Reaction ◽  
Reaction Times ◽  
Acid Catalyst ◽  
Zinc Nitrate ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
One Pot ◽  
Brönsted Acid

Tartaric acid–zinc nitrate has been found to be an efficient Brønsted acid-assisted Lewis acid catalytic system for the facile synthesis of β-amino carbonyl compounds through the one-pot Mannich reaction of aldehydes, aromatic amines and ketones in ethanol at room temperature. Remarkable enhancement of reactivity by tartaric acid (Brønsted acid) was observed in these reactions in the presence of anhydrous zinc nitrate (Lewis acid), due to coordination of the tartaric acid ligand to zinc ions increasing the acidity of the system. This procedure shows some advantages such as mild reaction conditions, short reaction times and high yields.

scholarly journals Enantioselective Mannich Reaction Promoted by Chiral Phosphinoyl-Aziridines

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 837 ◽  
Author(s):  
Aleksandra Buchcic ◽  
Anna Zawisza ◽  
Stanisław Leśniak ◽  
Justyna Adamczyk ◽  
Adam Marek Pieczonka ◽  
...  
Keyword(s):  
Phosphine Oxide ◽  
Mannich Reaction ◽  
Aromatic Aldehydes ◽  
Chiral Catalysts ◽  
Enantiomerically Pure ◽  
High Yields ◽  
High Level

In this study, a set of enantiomerically pure aziridines bearing a phosphine oxide moiety were prepared in high yields and tested as chiral catalysts in the direct asymmetric Mannich reaction of hydroxyacetone, an amine (p-anisidine), and various aromatic aldehydes. The appropriate Mannich adducts were formed in chemical yields from moderate to good with a high level of enantio- and diastereoselectivity. The best results were obtained using the catalysts bearing a free NH-aziridine subunit.

Stereoselective Synthesis of Quinolizidine Alkaloids: (–)-Lasubin II

2008 ◽  
Vol 63 (4) ◽  
pp. 425-430 ◽  
Author(s):  
Markus Weymann ◽  
Horst Kunz
Keyword(s):  
Mannich Reaction ◽  
Stereoselective Synthesis ◽  
Pure Form ◽  
Quinolizidine Alkaloids ◽  
Enantiomerically Pure ◽  
Quinolizidine Alkaloid

AbstractBased on a higly diastereoselective Mannich reaction of N-(3,4-dimethoxybenzylidene) 2,3,4,6- tetra-O-pivaloyl-β -D-galactopyranosylamine 3 with the Danishefsky diene the quinolizidine alkaloid lasubin II was synthesized in enantiomerically pure form in six steps.

Enantioselektive Katalyse, XVIII Der Einfluß nicht koordinierter Stereozentren auf die enantioselektive Hydrierung/Enantioselective Catalysis, XVIII The Influence of Non-Coordinated Stereocenters on the Enantioselective Hydrogenation

1998 ◽  
Vol 53 (2) ◽  
pp. 211-223 ◽  
Author(s):  
Ulrich Nagel ◽  
Christoph Roller
Keyword(s):  
Michael Addition ◽  
Enantioselective Hydrogenation ◽  
Palladium Complexes ◽  
Enantioselective Catalysis ◽  
Pyrrolidine Ring ◽  
Enantiomerically Pure ◽  
Stereogenic Centers ◽  
Methyl Phenyl ◽  
Phenyl Vinyl

Abstract 3,4-Bis{[2-(methyl-phenyl-oxophosphanyl)-ethyl]phenyl-phosphanyl}pyrrolidines have be­en synthesized by Michael Addition from the corresponding methyl-phenyl-vinyl-phosphane oxides and 3,4-bis(phenylphosphino)pyrrolidines. For purification of the ligands palladium complexes were used and with the enantiomerically pure ligands Rh complexes have been pre­pared. The catalyst has 6 stereogenic centers. In the hydrogenation of Z-α-acetamidocinnamic acid all six stereogenic centers have an influence on the enantioselectivity. The influence is strongest from the C stereocenters of the pyrrolidine ring. Less important are the stereogenic centers on the coordinated P atoms. The influence of the stereocenters on the non-coordinated P = O groups is the least, but it is not negligible. The ee values obtained with the ligands containing P = O groups are much lower than those obtained with ligands which are substituted only with aryl groups. Ketones are hydrogenated with only low ee’s.

Sign in / Sign up

Export Citation Format

Share Document