Petasis Reagent

Introduction

The Petasis reagent [¹] (dimethyl titanocene, Cp₂TiMe₂) is readily prepared by the reaction of methylmagnesium chloride [²] or methyllithium [³] with titanocene dichloride. It is used for transforming carbonyl groups to terminal al­kenes, [4] like the Tebbe reagent or Wittig reaction. Unlike the Wittig reaction, the Petasis reagent can react with a wide range of carbonyls, such as aldehydes, ketones, ­esters, and lactones including enolizable and acid-labile substrates. The Petasis reagent is also non-pyrophoric, relatively air- and water-stable, and can be used directly as a solution in toluene-THF.

The active olefinating reagent, Cp₂TiCH₂, can be prepared by heating the Petasis reagent in toluene or THF to 60-75 ˚C. The Petasis reaction can also be promoted by microwave irradiation.

Scheme 1

References

• 1a Petasis NA. Bzowej EI. J. Am. Chem. Soc.  1990,  112:  6392 
• 1b Petasis NA. Lu SP. Tetrahedron Lett.  1995,  36:  2393 
• 2 Payack JF. Hughes DL. Cai D. Cottrell IF. Verhoeven TR. Org. Synth.  2002,  79:  19 
• 3 Clauss K. Bestian H. Justus Liebigs Ann. Chem.  1962,  654:  8 
• 4 Hartley RC. McKiernan GJ. J. Chem. Soc., Perkin Trans. 1  2002,  2763 
• 5 Colson PJ. Hegedus LS. J. Org. Chem.  1993,  58:  5918 
• 6 Atarashi S. Choi JK. Ha DC. Hart FJ. Kuzmich D. Lee CS. Ramesh S. Wu SC. J. Am. Chem. Soc.  1997,  119:  6226 
• 7a Morency L. Barriault L. J. Org. Chem.  2005,  70:  8841 
• 7b Smith ABIII. Simon V. Org. Lett.  2006,  8:  3315 
• 8a Lambert WT. Hanson GH. Benayoud F. Burke SD. J. Org. Chem.  2005,  70:  9382 
• 8b Gaunt MJ. Jessiman AS. Orsini P. Tanner HR. Hook DF. Ley SV. Org. Lett.  2003,  5:  4819 
• 9 Heskamp BM. Veeneman GH. van der Marel GA. Van Boeckel CAA. Van Boom JH. Tetrahedron  1995,  51:  8397 
• 10 Johns BA. Pan YT. Elbein AD. Johnson CR. J. Am. Chem. Soc.  1997,  119:  4856 
• 11 Li X. Ohtake H. Takahashi H. Ikegami S. Synlett  2001,  1885 
• 12a Chenault HK. Chafin LF. J. Org. Chem.  1994,  59:  6167 
• 12b Chenault HK. Castro A. Chafin LF. Yang J. J. Org. Chem.  1996,  61:  5024 
• 13 Cook MJ. Fleming DW. Gallagher T. Tetrahedron Lett.  2005,  46:  297 
• 14 Martinez I. Howell AR. Tetrahedron Lett.  2000,  41:  5607 
• 15a Petasis NA. Bzowej EI. J. Org. Chem.  1992,  57:  1327 
• 15b Petasis NA. Akritopoulou I. Synlett  1992,  665 
• 15c Petasis NA. Bzowej EI. Tetrahedron Lett.  1993,  34:  943 
• 16a Davidson JEP. Anderson EA. Buhr W. Harrisson JR. O’Sullivan PT. Collins I. Green RH. Holmes AB. Chem. Commun.  2000,  629 
• 16b Anderson EA. Davidson JEP. Harrison JR. O’Sullivan PT. Burton JW. Holmes AB. Tetrahedron  2002,  58:  1943 
• 17 Petasis NA. Bzowej EI. Tetrahedron Lett.  1993,  34:  1721 
• 18 Petasis NA. Lu S.-P. Tetrahedron Lett.  1996,  37:  141 
• Few examples:
• 19a Smith AB. Mesaros EF. Meyer EA. J. Am. Chem. Soc.  2006,  128:  5292 
• 19b Smith ABIII. Simov V. Org. Lett.  2006,  8:  3315 
• 19c Smith ABIII. Minibiole KP. Verhoest PR. Beauchamp TJ. Org. Lett.  1999,  1:  913 
• 20 Nicolaou KC. Postema MHD. Claiborne CF. J. Am. Chem. Soc.  1996,  118:  1565 
• 21 (a) Taber DF. Kong S. Malcolm SC. J. Org. Chem.  1998,  63:  7953 
• 21 (b) Panda J. Ghosh S. J. Chem. Soc., Perkin Trans. 1  2001,  3013 
• 21 (c) Donohoe TJ. Guillermin J.-B. Frampton C. Walter DS. Chem. Commun.  2000,  465