Chlorobis(cyclooctene)rhodium dimer

Chlorobis(cyclooctene)rhodium dimer is an organorhodium compound with the formula Rh2Cl2(C8H14)4, where C8H14 is cis-cyclooctene. Sometimes abbreviated Rh2Cl2(coe)4, it is a red-brown, air-sensitive solid that is a precursor to many other organorhodium compounds and catalysts.

Chlorobis(cyclooctene)rhodium dimer
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.152.028
  • InChI=1S/4C8H14.2ClH.2Rh/c4*1-2-4-6-8-7-5-3-1;;;;/h4*1-2H,3-8H2;2*1H;;/p-2/b4*2-1-;;;;
    Key: ZFCBAJWXKUDJSW-XFCUKONHSA-L
  • C1CCCC=CCC1.C1CCCC=CCC1.C1CCCC=CCC1.C1CCCC=CCC1.[Cl-].[Cl-].[Rh].[Rh]
Properties
C32H56Cl2Rh2
Molar mass 717.50
Appearance red-brown solid
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H302, H312, H315, H319, H332, H335
P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P312, P304+P340, P305+P351+P338, P312, P321, P322, P330, P332+P313, P337+P313, P362, P363, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

The complex is prepared by treating an alcohol solution of hydrated rhodium trichloride with cyclooctene at room temperature.[1] The coe ligands are easily displaced by other more basic ligands, more so than the diene ligands in the related complex cyclooctadiene rhodium chloride dimer.

Catalyst for C-H activation

C-H activation is often catalyzed by chlorobis(cyclooctene)rhodium dimer as demonstrated in the synthesis of a strained bicyclic enamine.[2]

C–H bond activation Yotphan 2008
C–H bond activation Yotphan 2008

The synthesis of a mescaline analogue involves enantioselective annulation of an aryl imine via a C-H activation.[3]

The total synthesis of lithospermic acid employs "guided C-H functionalization" late stage to a highly functionalized system. The directing group, a chiral nonracemic imine, is capable of performing an intramolecular alkylation, which allows for the rhodium-catalyzed conversion of imine to the dihydrobenzofuran.[4]

Key step in synthesis of lithospermic acid
Key step in synthesis of lithospermic acid

References
  1. Van der Ent, A.; Onderdelinden, A. L. "Chlorobis(cyclooctene)rhodium(I) and di-μ-chlorobis[bis(cryclooctene)iridium] (I) complexes" Inorganic Syntheses 1973, volume 14, pp. 92-5. doi:10.1002/9780470132456.ch18
  2. Yotphan, Sirilata; Bergman, Robert G.; Ellman, Jonathan A. (2008). "The Stereoselective Formation of Bicyclic Enamines with Bridgehead Unsaturation via Tandem C–H Bond Activation/Alkenylation/ Electrocyclization". J. Am. Chem. Soc. 130 (8): 2452–2453. doi:10.1021/ja710981b. PMC 3062933. PMID 18247623.
  3. Ahrendt, Kateri A.; Bergman, Robert G.; Ellman, Jonathan A. (2003-04-01). "Synthesis of a Tricyclic Mescaline Analogue by Catalytic C−H Bond Activation". Organic Letters. 5 (8): 1301–1303. doi:10.1021/ol034228d. ISSN 1523-7060. PMID 12688744.
  4. O'Malley, S. J.; Tan, K. L.; Watzke, A.; Bergman, R. G.; Ellman, J. A. (2005). "Total Synthesis of (+)-Lithospermic Acid by Asymmetric Intramolecular Alkylation via Catalytic C-H Bond Activation". J. Am. Chem. Soc. 127 (39): 13496–13497. doi:10.1021/ja052680h. PMID 16190703.
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