Asymmetric cycloaddition reactions catalyzed by bifunctional thiourea and squaramide organocatalysts: recent advances

Held, Felix; Tsogoeva, Svetlana B.

doi:10.1039/c5cy01894c

Cited by 172 publications

(83 citation statements)

References 62 publications

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“…[3][4][5][6][7][8][9][10] As a result of the enormous activity in this area, organocatalysis has emerged as an efficient strategy in the production of enantiomerically enriched compounds with wide application in the synthesis of natural products and biologically active compounds. [18][19][20][21][22][23][24][25] The first reports discussing the propensities of ureas/thioureas to promote chemical transformations appeared more than fifteen years ago. [18][19][20][21][22][23][24][25] The first reports discussing the propensities of ureas/thioureas to promote chemical transformations appeared more than fifteen years ago.…”

Section: Introductionmentioning

confidence: 99%

“…1) and at least one of the reactants. 19,23,36,37 Many organocatalytically active thioureas are decorated with the 3,5-bis(trifluoromethyl)phenyl motif, which, as an electron accepting substituent, increases the H-bonding ability of the thiourea functionality and may also participate in π-π interactions. Thioureas are more efficient than urea derivatives due to their higher acidity ( pK a : 27 vs. pK a 21) showing almost 10 fold increase in complex stability.…”

Section: Introductionmentioning

confidence: 99%

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A novel thiourea type organocatalyst possessing a single NH functionality

et al. 2016

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A novel thiourea organocatalyst was rationally designed by altering a typical H-bonding pattern of thiourea derivatives and utilising the potential of the 3,5-bis(trifluoromethyl)phenyl motif to participate in the H-bond formation. This unique catalyst afforded the products of the α-amination and Michael reaction in excellent yields and with a high level of stereoselectivity. Although additional studies are necessary to establish the full potential of the catalyst and to broaden its application further, the presented results may indicate alternative routes for further exploration of the thiourea class of organocatalysts.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A novel thiourea type organocatalyst possessing a single NH functionality

et al. 2016

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“…This squaramide (-)-cinchonine catalyst is utilized in the conjugate addition of 1,3-dicarbonyl compounds tonitrostyrenes, to obtain products with high entioselectivities. This bifunctional catalyst probably operates in a similar mode to Takemoto's catalyst which contains a thiourea functionality [166,167].…”

Section: Squaramide Lead Compoundsmentioning

confidence: 99%

Squaryl Molecular Metaphors – Application to Rational Drug Design and Imaging Agents

Kitson¹

2017

J Diagn Imaging Ther

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Molecular Metaphors is the application of squaryl building blocks towards creative functional group chemistry to produce lead compounds and imaging agents. This strategy is applied to rational drug design and to various imaging agents that would normally contain conventional functional group chemistry. These, include carboxylic acids, α-amino acids, peptide bonds and phosphonates. Moreover, the squaryl metaphor is a precursor to complex organic molecules involving functional group interchange (FGI) and rearrangements. This article discusses the application of these metaphors in the area of neurochemistry, especially NMDA receptors. An important area of drug design is the inhibition of angiotensin II enzyme by the use of losartan. This commercial drug contains a tetrazole moiety that can be modified using the squaryl group to give a semisquarate derivative. These concepts can extend to the semisquarate of ibuprofen. Moreover, a discussion on peptidomimetics regarding the substitution of the peptide bond for squaramide allows for a change in the biological properties due to modification at the peptide bond. Furthermore, the topic on how squaryl metaphors can be exploited primarily by the central 1,3-hydroxyamide sequence to the generation of a novel class of HIV protease inhibitors. Also, squaryl metaphors can be used to develop potential inhibitors of glutathione and novel anti-migraine drugs. The discussion continues on the design of anticancer drugs: in particular, a novel class of metalloproteases, including phosphonates for semisquaramides, leading to squaryl nucleosides. This review concludes with the application of squaryl metaphors in the design of positron emission tomography (PET) and magnetic resonance imaging (MRI) agents towards theranostics. describe the ability of individual functional chemical groups to mimic other moieties [2,3]. KeywordsErlenmeyer rationalised these concepts and categorised isosteres into atoms, ions and molecules based on the valence level of electrons [4]. A further understanding by Friedman led to the term bioisosterism to include all atoms and molecules that fit the broadest definition of isosteres [5]. This approach was independent of whether the drug was an agonist or an antagonist towards biological activity.Moreover, Thornber applied the term bioisosterism to include subunits, groups or molecules that possess physicochemical properties of similar biological effects [6]. Finally, in 1991 Burger widened the definition of bioisosteres to include compounds or groups that possess similar molecular shapes and volumes independent of agonists or antagonists [7]. REVIEW ARTICLE Squaryl KitsonThese bioisosteres would require approximately the same distribution of electrons and give a high probability of generating comparable physical properties such as hydrophobicity [8]. Currently, bioisosterism is one of the most useful tools to the medicinal chemist in rational drug design and in particular regarding the carboxylic acid bioisosteres [9]. The carboxylic acid functional ...

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“…[10] In previous studies,o ur attention has been drawn to Werner complexes of cobalt(III) and 1,2-diamines.…”

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confidence: 99%

Werner Complexes with ω‐Dimethylaminoalkyl Substituted Ethylenediamine Ligands: Bifunctional Hydrogen‐Bond‐Donor Catalysts for Highly Enantioselective Michael Additions

et al. 2016

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The racemic carbonate complex [Co(en)2 O2 CO](+) Cl(-) (en=1,2-ethylenediamine) and (S)-[H3 NCH((CH2 )n NHMe2 )CH2 NH3 ](3+) 3 Cl(-) (n=1-4) react (water, charcoal, 100 °C) to give [Co(en)2 ((S)-H2 NCH((CH2 )n NHMe2 )CH2 NH2 )](4+) 4 Cl(-) (3 a-d H(4+) 4 Cl(-) ) as a mixture of Λ/Δ diastereomers that separate on chiral-phase Sephadex columns. These are treated with NaOH/Na(+) BArf (-) (BArf =B(3,5-C6 H3 (CF3 )2 )4 ) to give lipophilic Λ- and Δ-3 a-d(3+) 3 BArf (-) , which are screened as catalysts (10 mol %) for additions of dialkyl malonates to nitroalkenes. Optimal results are obtained with Λ-3 c(3+) 3 BArf (-) (CH2 Cl2 , -35 °C; 98-82 % yields and 99-93 % ee for six β-arylnitroethenes). The monofunctional catalysts Λ- and Δ-[Co(en)3 ](3+) 3 BArf (-) give enantioselectivities of <10 % ee with equal loadings of Et3 N. The crystal structure of Δ-3 a H(4+) 4 Cl(-) provides a starting point for speculation regarding transition-state assemblies.

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Asymmetric cycloaddition reactions catalyzed by bifunctional thiourea and squaramide organocatalysts: recent advances

Abstract: In this review, the recent developments in the field of enantioselective cycloaddition reactions using powerful bifunctional amine-thiourea and amine-squaramide organocatalysts have been described.

Cited by 172 publications

References 62 publications

A novel thiourea type organocatalyst possessing a single NH functionality

A novel thiourea type organocatalyst possessing a single NH functionality

Squaryl Molecular Metaphors – Application to Rational Drug Design and Imaging Agents

Werner Complexes with ω‐Dimethylaminoalkyl Substituted Ethylenediamine Ligands: Bifunctional Hydrogen‐Bond‐Donor Catalysts for Highly Enantioselective Michael Additions

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