Rhodium(I) Chemistry
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Rhodium(I) Chemistry. Sébastien Goudreau. Rhodium(I). Literature meeting : 13-02-2007. Rhodium. Number 45 [Kr]4d 8 5s 1 Hard silvery white and durable metal that has a high reflectance. (Use in jewellery) Does not form an oxide, is not attacked by acids. Very high melting point : 2236°C

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S bastien goudreau

Rhodium(I) Chemistry

Sébastien Goudreau

Rhodium(I)

Literature meeting : 13-02-2007


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Rhodium

  • Number 45

  • [Kr]4d85s1

  • Hard silvery white and durable metal that has a high reflectance.

  • (Use in jewellery)

  • Does not form an oxide, is not attacked by acids.

  • Very high melting point : 2236°C

  • It is the most expensive precious metal.

http://en.wikipedia.org/wiki/Rhodium


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Applications

  • The primary use of this element is as an alloying agent for hardening platinum and palladium.

  • It is used as an electrical contact material due to its low electrical resistance, low and stable contact resistance, and its high corrosion resistance.

  • Plated rhodium, made by electroplating or evaporation, is extremely hard and is used for optical instruments.

  • This metal finds use in jewelry and for decorations.

  • It is also a highly useful catalyst.

http://en.wikipedia.org/wiki/Rhodium


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History

  • Rhodium was discovered in 1803 by William Hyde Wollaston soon after his discovery of palladium.

  • Wollaston made this discovery in England using crude platinum ore that he presumably obtained from South America.

  • His procedure involved dissolving the ore in aqua regia (HCl + HNO3), neutralizing the acid with NaOH.

  • He then precipitated the platinum metal by adding NH4Cl, as ammonium chloroplatinate.

  • The element palladium was removed as palladium cyanide after treating the solution with mercuric cyanide.

  • The material that remained was a red rhodium(III) choride. (Greek rhodon meaning "Rose")

  • Wilkinson’s catalyst : RhCl(PPh3)3 : 1965

William Hyde Wollaston

Geoffrey Wilkinson

Nobel Prize 1973

Wilkinson et al. J. Org. Chen. Chem. Commun., 1965, 7, 131.

http://en.wikipedia.org/wiki/Rhodium


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Rhodium(I) in Organic Chemistry

  • C-H and C-C bond activation

  • Hydrorhodation

  • A) Hydrogenation

  • B) Hydroarylation

  • C) Hydroalkynation

  • D) Hydroacylation

  • E) Hydrosilylation

  • F) Hydroboration

  • 3) Addition

  • A) 1,4 addition

  • B) 1,2 addition

  • C) Coupling

  • 4) Sigmatropic Rearrangement

  • A) Cycloaddition

  • B) Alder-ene

5) p-Allyl chemistry

6) b-aryl elimination

Square plane


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1) C-H and C-C bond activation

Prof. David MilsteinThe Weizmann Institute of Science, Israel

(a) Milstein et al. Angew. Chem. Int. Ed.2007, 46, ASAP. (b) Bergman et al. J. Am. Chem. Soc.2006, 128, 2452. (c) Milstein et al. J. Am. Chem. Soc.2003, 125, 11041.


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2) Hydrorhodation

  • Hydrogenation

  • B) Hydroarylation

  • C) Hydroalkynation

  • D) Hydroacylation

  • E) Hydrosilylation

  • F) Hydroboration


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A) Hydrogenation

Zassinovich, Mestroni Chem. Rev.1992, 92, 1051 and references cited therein


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Enantioselective Hydrogenation

Burk et al. J. Am. Chem. Soc.1993, 115, 10125.


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B) Hydroarylation

Pfeffer et al. Chem. Rev.2002, 102, 1731.


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B) Hydroarylation : exemple

Pfeffer et al. Chem. Rev.2002, 102, 1731.


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B) Hydroarylation : exemple

Pfeffer et al. Chem. Rev.2002, 102, 1731.


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C) Hydroalkynation

Pfeffer et al. Chem. Rev.2002, 102, 1731.


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C) Hydroalkynation : exemples

Pfeffer et al. Chem. Rev.2002, 102, 1731.


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D) Hydroacylation

Pfeffer et al. Chem. Rev.2002, 102, 1731.


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D) Hydroacylation : exemples

Pfeffer et al. Chem. Rev.2002, 102, 1731.


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D) Hydroacylation : example

Pfeffer et al. Chem. Rev.2002, 102, 1731.


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Intramolecular Hydroacylation

Pfeffer et al. Chem. Rev.2002, 102, 1731.


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C) Hydrosilylation


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C) Hydrosilylation

Pfeffer et al. Chem. Rev.2002, 102, 1731.


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D) Hydroboration

Guiry et al. Adv. Synth. Catal.2005, 347, 609.


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D) Hydroboration

Guiry et al. Adv. Synth. Catal.2005, 347, 609.


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Hydrorhodation : Conclusion

  • Atom efficient

  • Mild conditions

  • Good alternative route

  • Regioselectivity : can be problematic

  • Enantioselectivity : can be very good


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2) Addition reaction

  • 1,4 addition

  • 1,2 addition

  • Coupling


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A) 1,4 addition reaction

M : Organoboron (organostannate, organosilane, organobismuth)

R : Aryl

Fagnou, Lautens Chem. Rev.2003, 103, 169.


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A) 1,4 Addition : exemples

Fagnou, Lautens Chem. Rev.2003, 103, 169.


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A) 1,4 Addition : examples

Fagnou, Lautens Chem. Rev.2003, 103, 169.


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A) 1,4 Addition : examples

Fagnou, Lautens Chem. Rev.2003, 103, 169.


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A) 1,4 Addition : examples

Fagnou, Lautens Chem. Rev.2003, 103, 169.


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A) 1,4 Addition : examples

Fagnou, Lautens Chem. Rev.2003, 103, 169.


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Krische’s chemistry


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Krische’s chemistry

Krische et al. J. Am. Chem. Soc.2002, 124, 15156.


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B) 1,2 Addition reaction

M : Organoboron (organostannate, organosilane, organobismuth)

R : Aryl

Fagnou, Lautens Chem. Rev.2003, 103, 169.


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B) 1,2 Addition : exemples

Fagnou, Lautens Chem. Rev.2003, 103, 169.


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B) 1,2 Addition : exemples

Ellman et al. J. Am. Chem. Soc.2005, 127, 1092.


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B) 1,2 Addition : exemples

(a) Fagnou, Lautens Chem. Rev.2003, 103, 169. (b) Iwasawa et al. J. Am. Chem. Soc.2006, 128, 8706.


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Krische’s chemistry

Krische et al. J. Am. Chem. Soc.2006, 128, 718.


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C) Coupling

Fagnou, Lautens Chem. Rev.2003, 103, 169.


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Addition reaction : Conclusion

  • Mild conditions : presence of water

  • Good enantioselectivity

  • Excess of organoboron needed


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4) Sigmatropic rearrangement

A) Cycloaddition

2+2+2

2+2+1 (Pauson-Khand)

3+2

4+2

5+2

6+1

4+2+2

Paul A. Wender

Stanford University, USA

B) Alder-ene


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Mecanism : [2+2+2]

Lautens et al.Chem. Rev.1996, 96, 49.


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[2+2+1] Cycloaddition : Pauson-Khand Reaction

Lautens et al.Chem. Rev.1996, 96, 49.


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[2+2+1] Cycloaddition : Pauson-Khand Reaction

Jeong et al. J. Am. Chem. Soc.2000, 122, 6771.


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[3+2] Cycloaddition

Wender et al.J. am. Chem. Soc.2006, 128, 14814.


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[4+2] Cycloaddition : Diels Alder

Mikami et al.J. Am. Chem. Soc.2006, 128, 12648.


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[5+2] Cycloaddition

Saito et al.J. Org. Chem.2006, 71, 6437.


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[6+1] cycloaddition

Wender et al.Angew. Chem. Int. Ed.2006, 45, 3957.


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[4+2+2] and [2+2+2+1] cycloaddition

Wender et al.J. Am. Chem. Soc.2006, 128, 5354.

Ojima et al. Org. Lett.2004, 6, 3589.


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B) Alder-ene

Zhang et al.J. Am. Chem. Soc.2002, 124, 8198.


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Conclusion

  • Access to a large variety of cycles

  • Regioselectivity : need linkers


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5) Allylic

(a) P.A. Evans et al.J. Am. Chem. Soc.2004, 126, 8642. (b) P.A. Evans et al. J. Am. Chem. Soc.2003, 125, 8974. (c) P.A. Evans et al.J. Am. Chem. Soc.2002, 124, 7882.


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6) b-aryl elimination

John F. Hartwig

Yale University, USA


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Conclusion

  • C-H and C-C bond activation

  • Hydrorhodation

  • A) Hydrogenation

  • B) Hydroarylation

  • C) Hydroalkynation

  • D) Hydroacylation

  • E) Hydrosilylation

  • F) Hydroboration

  • 3) Addition

  • A) 1,4 addition

  • B) 1,2 addition

  • C) Coupling

  • 4) Sigmatropic Rearrangement

  • A) Cycloaddition

  • B) Alder-ene

5) p-Allyl chemistry

6) b-aryl elimination

Square plane


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Conclusion


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