Misplaced Pages

Petasis reagent

Article snapshot taken from[REDACTED] with creative commons attribution-sharealike license. Give it a read and then ask your questions in the chat. We can research this topic together.

This is an old revision of this page, as edited by Citation bot (talk | contribs) at 12:07, 27 December 2010 (Citations: added: last1, first1, last2, first2, last3, first3, last4, first4. Tweaked: title, year, journal, volume, pages. stone). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Revision as of 12:07, 27 December 2010 by Citation bot (talk | contribs) (Citations: added: last1, first1, last2, first2, last3, first3, last4, first4. Tweaked: title, year, journal, volume, pages. stone)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)
Petasis reagent
Structural formula of the Petasis reagent
Structural formula of the Petasis reagent
Ball-and-stick model of the Petasis reagent
Ball-and-stick model of the Petasis reagent
Names
IUPAC name bis(η-cyclopentadienyl)dimethyltitanium
Other names dimethyl titanocene
Identifiers
CAS Number
3D model (JSmol)
ECHA InfoCard 100.204.841 Edit this at Wikidata
SMILES
  • C(C)(C)c.c1cccc1.c2cccc2
Properties
Chemical formula C12H16Ti
Molar mass 208.13 g/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards Irritant, incompatible with water and oxidizing agents
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Infobox references
Chemical compound

The Petasis reagent (not to be confused with the Petasis reaction) is dimethyl titanocene, Cp2TiMe2, readily prepared by the reaction of methylmagnesium chloride or methyllithium with titanocene dichloride:

Cp2TiCl2 + 2 "Me" → Cp2TiMe2 + 2 Cl

It is used for transforming carbonyl groups to terminal alkenes, much like the Tebbe reagent or Wittig reaction. Unlike the Wittig reaction, the Petasis reagent can react with a wide range of carbonyls, including aldehydes, ketones and esters. The Petasis reagent is also more air stable than the Tebbe reagent, and can be isolated as a pure solid, or used directly as a solution in toluene-THF.

The active olefinating reagent, Cp2TiCH2, is prepared by heating the Petasis reagent in toluene or THF to 60 °C.

The reaction mechanism is very similar to that of the Tebbe reagent, first yielding a titanium carbene which forms a four membered oxatitanacyclo and than releases the terminal alkene.

References

  1. N. A. Petasis and E. I. Bzowej (1990). "Titanium-mediated carbonyl olefinations. 1. Methylenations of carbonyl compounds with dimethyltitanocene". J. Am. Chem. Soc. 112 (17): 6392–6394. doi:10.1021/ja00173a035.
  2. Payack, J. F.; Hughes, D. L.; Cai, D.; Cottrell, I. F.; Verhoeven, T. R. (2002). "Dimethyltitanocene". Organic Syntheses. 79: 19{{cite journal}}: CS1 maint: multiple names: authors list (link).
  3. Claus, K.; Bestian, H. (1962). "Über die Einwirkung von Wasserstoff auf einige metallorganische Verbindungen und Komplexe". Justus Liebigs Ann. Chem. 654: 8. doi:10.1002/jlac.19626540103.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. Hartley, R. C.; Li, J.; Main, C. A.; McKiernan, G. J. (2007). "Titanium carbenoid reagents for converting carbonyl groups into alkenes". Tetrahedron. 63: 4825–4864. doi:10.1016/j.tet.2007.03.015.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. Meurer, Eduardo Cesar; Santos, Leonardo Silva; Pilli, Ronaldo Aloise; Eberlin, Marcos N. (2003). "Probing the Mechanism of the Petasis Olefination Reaction by Atmospheric Pressure Chemical Ionization Mass and Tandem Mass Spectrometry". Organic Letters. 5: 1391. doi:10.1021/ol027439b.
Categories:
Petasis reagent Add topic