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Petasis reagent

Petasis reagent
Systematic name bis(n5-2,4-cyclopentadien-1-yl)
Other names dimethyl titanocene
Molecular formula C12H16Ti
SMILES C[Ti](C)(C)c.c1cccc1.c2cccc2
Molar mass 208.13 g/mol
Appearance yellow solution in toluene
CAS number [ 1271-66-5]
Solubility in water slowly hydrolyzes
Other solvents soluble in toluene
MSDS External MSDS
Main hazards Irritant, incompatible with

water and oxidizing agents

NFPA 704
Flash point  ?°C
R/S statement R: ?
S: ?
RTECS number  ?
Supplementary data page
Structure and
n, εr, etc.
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Related compounds
Related compounds  ?
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and references

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. 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.

Additional recommended knowledge

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


  • Payack, J. F.; Hughes, D. L.; Cai, D.; Cottrell, I. F.; Verhoeven, T. R. (2002). "Dimethyltitanocene". Org. Synth. 79: 19. 
  • 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.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Petasis_reagent". A list of authors is available in Wikipedia.
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