scholarly journals RuCl3 · nH2O as Catalyst for Diastereoselective Direct Aldol Reaction: An Efficient Route to Hormone Steroid Derivatives

2011 ◽  
Vol 2011 ◽  
pp. 1-5
Author(s):  
Khalil Tabatabaeian ◽  
Elahe Keshavarz ◽  
Manouchehr Mamaghani ◽  
Nosrat O. Mahmoodi
Keyword(s):  
Aldol Reaction ◽  
Reaction Times ◽  
Catalytic Efficiency ◽  
Aromatic Aldehydes ◽  
Direct Aldol Reaction ◽  
Efficient Route

-catalyzed regio- and diastereoselective direct aldol reaction of progesterone with aromatic aldehydes has been developed in good yields (58–78%). Advantages of this method include catalytic efficiency, short reaction times, and ease of operation and workup.

Synthesis of 1,2-Diamine Bifunctional Catalysts for the Direct Aldol Reaction Through Probing the Remote Amide Hydrogen

2019 ◽  
Vol 6 (2) ◽  
pp. 171-176
Author(s):  
Rajasekhar Dodda ◽  
Sampak Samanta ◽  
Matthew Su ◽  
John Cong-Gui Zhao
Keyword(s):  
Hydrogen Bonding ◽  
Catalytic Activity ◽  
Aldol Reaction ◽  
Catalytic Efficiency ◽  
Aldol Reactions ◽  
Catalyst Loading ◽  
Bifunctional Catalysts ◽  
Amide Hydrogen ◽  
Highly Efficient ◽  
Direct Aldol Reaction

Background: While proline can catalyze the asymmetric direct aldol reactions, its catalytic activity and catalyst turnover are both low. To improve the catalytic efficiency, many prolinebased organocatalysts have been developed. In this regard, prolinamide-based bifunctional catalysts have been demonstrated by us and others to be highly efficient catalysts for the direct aldol reactions. Results: Using the β-acetamido- and β-tosylamidoprolinamide catalysts, the highly enantio- and diastereoselective direct aldol reactions between enolizable ketones and aldehydes were achieved (up to >99% ee, 98:2 dr). A low catalyst loading of only 2-5 mol % of the β-tosylamidoprolinamide catalyst was needed to obtain the desired aldol products in good to high yields and high stereoselectivities. Methods: By carefully adjusting the hydrogen bonding ability of the remote β-amide hydrogen of the 1,2-diamine-based prolinamide bifunctional catalysts, the catalytic activity and the asymmetric induction of these catalysts were significantly improved for the direct aldol reaction between aldehydes and enolizable ketones. Conclusion: Some highly efficient 1,2-diamine-based bifunctional prolinamide catalysts have been developed through probing the remote β-amide hydrogen for its hydrogen bonding capability. These catalysts are easy to synthesize and high enantioselectivities may be achieved at very low catalyst loadings.

ChemInform Abstract: Highly Enantioselective Proline-Catalyzed Direct Aldol Reaction of Chloroacetone and Aromatic Aldehydes.

ChemInform ◽  
2012 ◽  
Vol 43 (37) ◽  
pp. no-no
Author(s):  
Angel Martinez-Castaneda ◽  
Belen Poladura ◽  
Humberto Rodriguez-Solla ◽  
Carmen Concellon ◽  
Vicente del Amo
Keyword(s):  
Aldol Reaction ◽  
Aromatic Aldehydes ◽  
Direct Aldol Reaction

Highly Enantioselective Proline-Catalysed Direct Aldol Reaction of Chloroacetone and Aromatic Aldehydes

2012 ◽  
Vol 18 (17) ◽  
pp. 5188-5190 ◽  
Author(s):  
Ángel Martínez-Castañeda ◽  
Belén Poladura ◽  
Humberto Rodríguez-Solla ◽  
Carmen Concellón ◽  
Vicente del Amo
Keyword(s):  
Aldol Reaction ◽  
Aromatic Aldehydes ◽  
Direct Aldol Reaction

scholarly journals Bioinspired Polymer-Bound Organocatalysts for Direct Asymmetric Aldol Reaction: Experimental and Computational Studies

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 398
Author(s):  
Ganhong Du ◽  
Jun Ling ◽  
Fangyu Hu ◽  
Keyuan Liu ◽  
Long Ye ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Aldol Reaction ◽  
Catalytic Efficiency ◽  
Aromatic Aldehydes ◽  
Relative Energy ◽  
Catalyst Loading ◽  
Polymer Backbone ◽  
Asymmetric Aldol ◽  
Tertiary Amide ◽  
Asymmetric Aldol Reaction

A series of poly(2-oxazoline) (POX) derivatives bearing prolinamide pendants were designed as organocatalysts and evaluated in the direct asymmetric aldol reaction between aromatic aldehydes and cyclic ketones. The structural variation of the alkyl spacer connecting the polymer backbone with the catalytic unit was applied so as to deduce structure–performance relationships combined with comparable experiments from model catalysts. Results showed that the POX-bound prolinamides can promote the aldol reaction more effectively as compared to their small-molecular and non-POX-bound analogs. The catalyst P3 containing the pyrrolidine moiety closer to the tertiary amide backbone exhibited the overall best catalytic efficiency, affording anti-products in 84% yield with 89% ee in the representative aldol addition of cyclohexanone to 4-nitrobenzaldehyde at a 10 mol.% catalyst loading. Furthermore, the influence of trifluoroacetic acid as an additive on the asymmetric transformation was investigated. Theoretical calculations revealed that the protonation of the aldehyde carbonyl group switched the activation mode of the aldol acceptor through hydrogen bond interactions, thereby changing the relative energy barrier of the enamine/aldehyde reaction transition states, which accounted well for the significant improvement in the enantioselectivity of the acidic additives observed experimentally.

An Efficient Synthesis of Pyrano[c]chromenediones and [1,3]Dioxolo[g]chromeneones Catalyzed by Nickel(II) Chromite Nanoparticles Through a Three-Component Domino Reaction

2021 ◽  
Vol 24 ◽  
Author(s):  
Bahareh Saeedi ◽  
Shahrzad Abdolmohammadi ◽  
Zohreh Mirjafary ◽  
Reza Kia-Kojoori
Keyword(s):  
Condensation Reaction ◽  
Reaction Times ◽  
Catalytic Efficiency ◽  
Aromatic Aldehydes ◽  
13C Nmr Spectroscopy ◽  
Recyclable Catalyst ◽  
Lewis Base ◽  
Domino Reaction ◽  
Elemental Analyses ◽  
High Yields

Background: The importance of fused chromene motifs in bioactive compounds highlighted the current research to explore novel methods for the construction of these heterocyclic scaffolds. Regarding the attractive features of developing novel methodological approaches in the presence of heterogeneous nanocatalysts, we will try to synthesize 4-aryl-3,4-dihydro-2H,5H-pyrano[3,2-c]chromene-2,5-diones and 8-aryl-7,8-dihydro-6H-[1,3]dioxolo[4,5-g]chromene-6-ones through this method. Objective: The aim of the present research was to prove the catalytic efficiency of the synthesized nickel(II) chromite nanoparticles (NiCr2O4 NPs) as bifunctional Lewis acid-Lewis base catalyst in the synthesis of pyrano[c]chromenediones and [1,3]dioxolo[g]chromeneones. Methods: Pyrano[c]chromenediones and [1,3]dioxolo[g]chromeneones were conveniently prepared from a three-component condensation reaction between aromatic aldehydes, meldrum’s acid, and active methylene compounds including 4-hydroxycoumarin or 3,4-methylenedioxyphenol using NiCr2O4 NPs as an efficient, easily obtained, and recyclable catalyst, under ethanol-drop grinding at room temperature. The synthesized compounds were characterized by IR, 1H and 13C NMR spectroscopy, and also by elemental analyses. Results: A number of 4-aryl-3,4-dihydro-2H,5H-pyrano[3,2-c]chromene-2,5-diones and 8-aryl-7,8-dihydro-6H-[1,3]dioxolo[4,5-g]chromene-6-ones were effectively synthesized as target compounds in high yields. Conclusion: This study provides a simple, inexpensive and NiCr2O4 NPs catalyzed route to synthesis pyrano[c]chromenediones and [1,3]dioxolo[g]chromeneones in high yields. The reaction offers several benefits including simple experimental procedures, higher yields, shorter reaction times and use of easily obtained and recyclable catalyst compared with previously reported methods and has a great foreground of development.

Synthesis of novel chiral bithiophenebased phosphine oxides as Lewis bases in organocatalytic stereoselective reactions

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Sergio Rossi ◽  
Maurizio Benaglia ◽  
Roberto Cirilli ◽  
Tiziana Benincori
Keyword(s):  
Phosphine Oxide ◽  
Aldol Reaction ◽  
Enantiomeric Excess ◽  
Catalytic Efficiency ◽  
Phosphine Oxides ◽  
Aromatic Rings ◽  
Enantiomerically Pure ◽  
Lewis Bases ◽  
Direct Aldol Reaction ◽  
Stereoselective Reactions

Abstract Novel enantiomerically pure tetramethylbithiophene diphosphine oxides (tetraMe-BITIOPO) featuring differently substituted aromatic rings at the phosphorous atoms were synthesized, fully characterized and isolated in enantiomerically pure form. The new Lewis bases were tested as organocatalysts in two different reactions involving trichlorosilyl compounds. The introduction of electron donating substituents on the aromatic rings connected to the phosphine oxide groups positively affected the chemical and stereochemical catalytic efficiency of these ligands. The new catalysts were able to promote the allylation of aldehydes with allyltrichlorosilane in up to 76% yield and up to 86% enantiomeric excess (ee), and the direct aldol reaction to afford β-hydroxy ketones in high diastereoselectivity (up to 88:12 anti:syn ratio) and up to 72% ee.

Sign in / Sign up

Export Citation Format

Share Document