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词条 Thiourea organocatalysis
释义

  1. History

  2. Catalyst-substrate interactions

  3. Advantages of thiourea organocatalysts

  4. Substrates

  5. Catalysts

  6. Further reading

  7. References

Within the area of organocatalysis, (thio)urea organocatalysis describes the use of ureas and thioureas to accelerate and stereochemically alter organic transformations. The effects arise through hydrogen-bonding interactions between the substrate and the (thio)urea. Unlike classical catalysts, these organocatalysts interact by non-covalent interactions, especially hydrogen bonding ("partial protonation"). The scope of these small-molecule H-bond donors termed (thio)urea organocatalysis covers both non-stereoselective and stereoselective applications.[1]

History

Pioneering contributions were made by Kelly, Etter, Jorgensen, Hine, Curran, Göbel, and De Mendoza (see review articles cited below) on hydrogen bonding interactions of small, metal-free compounds with electron-rich binding sites. Peter R. Schreiner and co-workers identified and introduced electron-poor thiourea derivatives as hydrogen-bonding organocatalysts. Schreiner's thiourea, N,N-bis[[3,5-bis(trifluormethyl)phenyl thiourea, combines all structural features for double H-bonding mediated organocatalysis:

  • electron-poor
  • rigid structure
  • non-coordinating, electron withdrawing substituents in 3,4, and/or 5 position of a phenyl ring
  • the 3,5-bis(trifluoromethyl)phenyl-group is the preferred substituent

Catalyst-substrate interactions

Hydrogen-bonding between thiourea derivatives and carbonyl substrates involve two hydrogen bonds provided by coplanar amino substituents in the (thio)urea.[2][3][4]
[5] Squaramides engage in double H-bonding interactions and are often superior to thioureas.[6]

Advantages of thiourea organocatalysts

Thio)ureas are green and sustainable catalysts. When effective, they can offer these advantages:

  • absence of product inhibition due to weak enthalpic binding, but specific binding-“recognition“
  • low catalyst-loading (down to 0.001 mol%)[3]
  • high TOF (Turn-Over-Frequency) values (up to 5,700 h−1)[3]
  • simple and inexpensive synthesis from primary amine functionalized (chiral-pool) starting materials and isothiocyanates
  • easy to modulate and to handle (bench-stable), no inert gas atmosphere required
  • immobilization on a solid phase (polymer-bound organocatalysts), catalyst recovery and reusability [3]
  • catalysis under almost neutral conditions (pka thiourea 21.0) and mild conditions, acid-sensitive substrates are tolerated
  • metal-free, nontoxic (compare traditional metal-containing Lewis-acid catalysts)
  • water-tolerant, even catalytically effective in water or aqueous media.[8]

Substrates

H-bond accepting substrates include carbonyl compounds, imines, nitroalkenes. The Diels-Alder reaction is one process that can benefit from (thio)urea catalysts.

Catalysts

A broad variety of monofuctional and bifunctional (concept of bifunctionality) chiral double hydrogen-bonding (thio)urea organocatalysts have been developed to accelerate various synthetically useful organic transformations

{{Gallery
|lines=4
|File:wikipedia jacobsen2 polymer thiourea.png|1998: Jacobsen's chiral (polymer-bound) Schiff base thiourea derivative for asymmetric Strecker reactions.[9][10]
|File:wikipedia Takemoto2.png|2003: Takemoto's bifunctional chiral thiourea derivative, catalysis of asymmetric Michael- and Aza-Henry reactions.[11]
|File:Wikipedia Nagasawa2.png|2004: Nagasawa's chiral bis-thiourea organocatalyst, catalysis of asymmetric Baylis-Hillman reactions.[12]
|File:wikipedia Nagasawa guanidine.png|2005: Nagasawa's bifunctional thiourea functionalized guanidine, asymmetric catalysis of Henry(Nitroaldol)reactions.[13]
|File:wikipedia Ricci alcohol thiourea.png|2005: Ricci's chiral thiourea derivative with additional hydroxy-group, enantioselective Friedel-Crafts alkylation of indols with nitroalkenes.[14]
|File:Wang binapthol thioharnstoff.png|2005: Wei Wang's bifunctional binaphthyl-thiourea derivative, asymmetric catalysis of Morita-Baylis-Hillman reactions.[15]
|File:wikipedia Connon2 alkaloid thioharnstoff.png|2005: Soos's, Connon and Dobson's bifunctional thiourea functionalized Cinchona alkaloid, asymmetric additions of nitroalkanes to chalcones[16] as well as malonates to nitroalkenes [17]
|File:wikipedia Yong Tang pyrrolidine Thioharnstoff.png|2006: Yong Tang's chiral bifunctional pyrrolidine-thiourea, enantioselective Michael additions of cyclohexanone to nitroolefins.[18]
|File:wikipedia berkessel bisthioharnstoff.png|2006: Berkessel's chiral isophoronediamine-derived bisthiourea derivative, catalysis of asymmetric Morita-Baylis-Hillman reactions.[19]
|File:wikipedia Takemoto polymer thiourea.png|2006: Takemoto's PEG-bound chiral thiourea, asymmetric catalysis of (tandem-) Michael reactions of trans-β-nitrostyrene, aza-Henry reactions.[20]
|File:wikipedia kotke polymer thiourea.png|2007: Kotke/Schreiner, polystyrene-bound, recoverable and reusable thiourea derivative for organocatalytic tetrahydropyranylation of alcohols.[3]
|File:wikipedia wanka adamantane thiourea.png|2007: Wanka/Schreiner, chiral peptidic adamantane-based thiourea, catalysis of Morita-Baylis-Hillman reactions.[21]
|File:Takemoto bifunctional hydroxy thiourea.png|2007: Takemoto's chelating bifunctional hydroxy-thiourea for enantioselective Petasis-type reaction of quinolines.[22]
|File:Catalysts of Ma Jun-An.jpg|2007: Ma Jun-An's Chiral Bifunctional Primary and tertiary Amine-thiourea Catalysts Based on Saccharides.[23][24]
}}

Further reading

  • {{cite journal | author = Christian M. Kleiner, Peter R. Schreiner|title=Hydrophobic amplification of noncovalent organocatalysis|journal=Chem. Commun.|year=2006|pages=4315–4017|doi=}}
  • {{cite journal | author = Z. Zhang and P. R. Schreiner | title = Thiourea-Catalyzed Transfer Hydrogenation of Aldimines | year = 2007 | journal = Synlett | volume = 2007| issue = 9 | pages = 1455–1457 | doi = 10.1055/s-2007-980349}}
  • {{cite journal|last=Wanka|first=Lukas|author2=Chiara Cabrele |author3=Maksims Vanejews |author4=Peter R. Schreiner |year=2007|title=γ-Aminoadamantanecarboxylic Acids Through Direct C–H Bond Amidations|journal=European Journal of Organic Chemistry|volume=2007|issue=9|pages=1474–1490|issn=1434-193X|doi=10.1002/ejoc.200600975}}

References

1. ^{{cite book|last1=Kotke|first1=Mike|last2=Schreiner|first2=Peter R.|title=Hydrogen Bonding in Organic Synthesis|chapter-url=http://eu.wiley.com/WileyCDA/WileyTitle/productCd-352731895X.html|date=October 2009|isbn=978-3-527-31895-7|pages=141 to 251|chapter=(Thio)urea Organocatalysts|editor=Petri M. Pihko}}
2. ^Alexander Wittkopp, Peter R. Schreiner, "Diels-Alder Reactions in Water and in Hydrogen-Bonding Environments", book chapter in "The Chemistry of Dienes and Polyenes" Zvi Rappoport (Ed.), Volume 2, John Wiley & Sons Inc.; Chichester, 2000, 1029-1088. {{ISBN|0-471-72054-2}}.
Alexander Wittkopp, "Organocatalysis of Diels-Alder Reactions by Neutral Hydrogen Bond Donors in Organic and Aqueous Solvents", dissertation written in German, Universität Göttingen, 2001. English abstract/download:  
Peter R. Schreiner, review: "Metal-free organocatalysis through explicit hydrogen bonding interactions", Chem. Soc. Rev. 2003, 32, 289-296. abstract/download: 
{{cite journal | author = M. Kotke and P. R. Schreiner | title = Acid-free, organocatalytic acetalization | year = 2006 | journal = Tetrahedron | volume = 62 | issue = 2–3 | pages = 434–439 | url = http://www.sciencedirect.com/science/article/B6THR-4HDG975-4/2/d9db0fc4379cd0c124c20885ec23e566 | doi = 10.1016/j.tet.2005.09.079}}{{cite journal | author = M. P. Petri | title = Activation of Carbonyl Compounds by Double Hydrogen Bonding: An Emerging Tool in Asymmetric Catalysis | year = 2004 | journal = Angewandte Chemie International Edition | volume = 43 | issue = 16 | pages = 2062–2064 | doi = 10.1002/anie.200301732 | pmid=15083451}}
Yoshiji Takemoto, review: "Recognition and activation by ureas and thioureas: stereoselective reactions using ureas and thioureas as hydrogen-bonding donors", Org. Biomol. Chem. 2005, 3, 4299-4306. abstract/download:  {{Cite journal | volume = 45 | issue = 10 | pages = 1520–1543 | author = Mark S. Taylor, Eric N. Jacobsen | title = Asymmetric Catalysis by Chiral Hydrogen-Bond Donors | journal = Angewandte Chemie International Edition | year = 2006 | doi = 10.1002/anie.200503132 | pmid=16491487}}{{cite journal | author = J. C. Stephen | title = Organocatalysis Mediated by (Thio)urea Derivatives | year = 2006 | journal = A European Journal | volume = 12 | issue = 21 | pages = 5418–5427 | doi = 10.1002/chem.200501076 | pmid=16514689}}
3. ^1 2 3 4 {{cite journal|last=Kotke|first=Mike|author2=Peter Schreiner |year=2007|title=Generally Applicable Organocatalytic Tetrahydropyranylation of Hydroxy Functionalities with Very Low Catalyst Loading|journal=Synthesis|volume=2007|issue=5|pages=779–790|issn=0039-7881|doi=10.1055/s-2007-965917}}
4. ^1 {{cite journal|last=Schreiner|first=Peter R.|author2=Alexander Wittkopp |year=2002|title=H-Bonding Additives Act Like Lewis Acid Catalysts|journal=Organic Letters|volume=4|issue=2|pages=217–220|issn=1523-7060|pmid=11796054|doi=10.1021/ol017117s}}
5. ^{{cite book|last=Kotke|first=Mike|title=Hydrogen-Bonding (Thio)urea Organocatalysts in Organic Synthesis : State of the art and Practical Methods for Acetalization, Tetrahydropyranylation, and Cooperative Epoxide Alcoholysis|url=http://geb.uni-giessen.de/geb/volltexte/2010/7835/|accessdate=2010-11-12|date=Ph.D. 2009|publisher=University Giessen/Germany}}
6. ^{{cite journal|authors=Chauhan, P.; Mahajan, S.; Kaya, U.; Hack, D.; Enders, D.|title=Bifunctional Amine-Squaramides: Powerful Hydrogen-Bonding Organocatalysts for Asymmetric Domino/Cascade Reactions|journal=Adv. Synth. Catal.|year=2015|volume=357|issue=2–3|pages=253–281|doi=10.1002/adsc.201401003}}
7. ^{{cite journal|last=Wittkopp|first=Alexander|author2=Peter R. Schreiner |year=2003|title=Metal-Free, Noncovalent Catalysis of Diels–Alder Reactions by Neutral Hydrogen Bond Donors in Organic Solvents and in Water|journal=Chemistry: A European Journal|volume=9|issue=2|pages=407–414|issn=0947-6539|doi=10.1002/chem.200390042|pmid=12532289}}
8. ^{{cite journal | author = A. Wittkopp and P. R. Schreiner | title = Metal-Free, Noncovalent Catalysis of Diels-Alder Reactions by Neutral Hydrogen Bond Donors in Organic Solvents and in Water | year = 2003 | journal = A European Journal | volume = 9 | issue = 2 | pages = 407–414 | doi = 10.1002/chem.200390042 | pmid=12532289}}
9. ^{{cite journal|last=Sigman|first=Matthew S.|author2=Eric N. Jacobsen |year=1998|title=Schiff Base Catalysts for the Asymmetric Strecker Reaction Identified and Optimized from Parallel Synthetic Libraries|journal=Journal of the American Chemical Society|volume=120|issue=19|pages=4901–4902|issn=0002-7863|doi=10.1021/ja980139y}}
10. ^{{cite journal|last=Sigman|first=Matthew S.|author2=Petr Vachal |author3=Eric N. Jacobsen |year=2000|title=A General Catalyst for the Asymmetric Strecker Reaction|journal=Angewandte Chemie International Edition|volume=39|issue=7|pages=1279–1281|issn=1433-7851|doi=10.1002/(SICI)1521-3773(20000403)39:7<1279::AID-ANIE1279>3.0.CO;2-U|pmid=10767031}}
11. ^{{cite journal|last=Okino|first=Tomotaka|author2=Yasutaka Hoashi |author3=Yoshiji Takemoto |year=2003|title=Enantioselective Michael Reaction of Malonates to Nitroolefins Catalyzed by Bifunctional Organocatalysts|journal=Journal of the American Chemical Society|volume=125|issue=42|pages=12672–12673|issn=0002-7863|pmid=14558791|doi=10.1021/ja036972z}}
12. ^{{cite journal|last=Sohtome|first=Yoshihiro|author2=Aya Tanatani |author3=Yuichi Hashimoto |author4=Kazuo Nagasawa |year=2004|title=Development of bis-thiourea-type organocatalyst for asymmetric Baylis–Hillman reaction☆|journal=Tetrahedron Letters|volume=45|issue=29|pages=5589–5592|issn=0040-4039|doi=10.1016/j.tetlet.2004.05.137}}
13. ^{{cite journal|last=Sohtome|first=Yoshihiro|author2=Yuichi Hashimoto |author3=Kazuo Nagasawa |year=2005|title=Guanidine-Thiourea Bifunctional Organocatalyst for the Asymmetric Henry (Nitroaldol) Reaction|journal=Advanced Synthesis & Catalysis|volume=347|issue=11–13|pages=1643–1648|issn=1615-4150|doi=10.1002/adsc.200505148}}
14. ^{{cite journal|last=Herrera|first=Raquel P.|author2=Valentina Sgarzani |author3=Luca Bernardi |author4=Alfredo Ricci |year=2005|title=Catalytic Enantioselective Friedel-Crafts Alkylation of Indoles with Nitroalkenes by Using a Simple Thiourea Organocatalyst|journal=Angewandte Chemie International Edition|volume=44|issue=40|pages=6576–6579|issn=1433-7851|doi=10.1002/anie.200500227|pmid=16172992}}
15. ^{{cite journal|last=Wang|first=Jian|author2=Hao Li |author3=Xinhong Yu |author4=Liansuo Zu |author5=Wei Wang |year=2005|title=Chiral Binaphthyl-Derived Amine-Thiourea Organocatalyst-Promoted Asymmetric Morita−Baylis−Hillman Reaction|journal=Organic Letters|volume=7|issue=19|pages=4293–4296|issn=1523-7060|pmid=16146410|doi=10.1021/ol051822+}}
16. ^{{cite journal|last=Vakulya|first=Benedek|author2=Szilárd Varga |author3=Antal Csámpai |author4=Tibor Soós |year=2005|title=Highly Enantioselective Conjugate Addition of Nitromethane to Chalcones Using Bifunctional Cinchona Organocatalysts|journal=Organic Letters|volume=7|issue=10|pages=1967–1969|issn=1523-7060|pmid=15876031|doi=10.1021/ol050431s}}
17. ^{{cite journal|last=McCooey|first=Séamus H.|author2=Stephen J. Connon |year=2005|title=Urea- and Thiourea-Substituted Cinchona Alkaloid Derivatives as Highly Efficient Bifunctional Organocatalysts for the Asymmetric Addition of Malonate to Nitroalkenes: Inversion of Configuration at C9 Dramatically Improves Catalyst Performance|journal=Angewandte Chemie International Edition|volume=44|issue=39|pages=6367–6370|issn=1433-7851|doi=10.1002/anie.200501721|pmid=16136619}}
18. ^{{cite journal|last=Cao|first=Chun-Li |author2=Meng-Chun Ye |author3=Xiu-Li Sun |author4=Yong Tang|year=2006|title=Pyrrolidine−Thiourea as a Bifunctional Organocatalyst: Highly Enantioselective Michael Addition of Cyclohexanone to Nitroolefins|journal=Organic Letters|volume=8|issue=14|pages=2901–2904|issn=1523-7060|pmid=16805512|doi=10.1021/ol060481c}}
19. ^{{cite journal|last=Berkessel|first=Albrecht|author2=Katrin Roland |author3=Jörg M. Neudörfl |year=2006|title=Asymmetric Morita−Baylis−Hillman Reaction Catalyzed by Isophoronediamine-Derived Bis(thio)urea Organocatalysts|journal=Organic Letters|volume=8|issue=19|pages=4195–4198|issn=1523-7060|pmid=16956185|doi=10.1021/ol061298m}}
20. ^{{cite journal|last=Miyabe|first=Hideto|author2=Sayo Tuchida |author3=Masashige Yamauchi |author4=Yoshiji Takemoto |year=2006|title=Reaction of Nitroorganic Compounds Using Thiourea Catalysts Anchored to Polymer Support|journal=Synthesis|volume=2006|issue=19|pages=3295–3300|issn=0039-7881|doi=10.1055/s-2006-950196}}
21. ^{{cite journal|last=Wanka|first=Lukas|author2=Chiara Cabrele |author3=Maksims Vanejews |author4=Peter R. Schreiner |year=2007|title=γ-Aminoadamantanecarboxylic Acids Through Direct C–H Bond Amidations|journal=European Journal of Organic Chemistry|volume=2007|issue=9|pages=1474–1490|issn=1434-193X|doi=10.1002/ejoc.200600975}}
22. ^{{cite journal|last=Yamaoka|first=Yousuke|author2=Hideto Miyabe |author3=Yoshiji Takemoto |year=2007|title=Catalytic Enantioselective Petasis-Type Reaction of Quinolines Catalyzed by a Newly Designed Thiourea Catalyst|journal=Journal of the American Chemical Society|volume=129|issue=21|pages=6686–6687|issn=0002-7863|pmid=17488015|doi=10.1021/ja071470x}}
23. ^{{cite journal|last=Liu|first=Kun |author2=Han-Feng Cui |author3=Jing Nie |author4=Ke-Yan Dong |author5=Xiao-Juan Li |author6=Jun-An Ma|year=2007|title=Highly Enantioselective Michael Addition of Aromatic Ketones to Nitroolefins Promoted by Chiral Bifunctional Primary Amine-thiourea Catalysts Based on Saccharides|journal=Organic Letters|volume=9|issue=5|pages=923–925|issn=1523-7060|pmid=17288432|doi=10.1021/ol0701666}}
24. ^{{cite journal|last=Li|first=Xiao-Juan |author2=Kun Liu |author3=Hai Ma |author4=Jing Nie |author5=Jun-An Ma|year=2008|title=Highly Enantioselective Michael Addition of Malonates to Nitroolefins Catalyzed by Chiral Bifunctional Tertiary Amine-Thioureas Based on Saccharides|journal=Synlett|volume=2008|issue=20|pages=3242–3246|issn=0936-5214|doi=10.1055/s-0028-1087370}}
{{DEFAULTSORT:Thiourea Organocatalysis}}

2 : Ureas|Catalysis
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