Diene-Ligated Iridium Complexes as Catalysts for Allylation and Methallylation Reactions of Ketones

Abstract

An iridium-catalyzed allylation reactions of ketones using dienes as ligands has been developed. A variety of ketones underwent allylation and methallylation reactions at room temperature in good yields under these conditions. Competition experiments demonstrate that the reaction is selective for electron-deficient ketones.

Key words

iridium - allylation - diene ligands - boric acid

References

• For reviews, see:
• 1a Johnson JB. Rovis T. Angew. Chem. Int. Ed.  2008,  47:  840 
• 1b Defieber C. Grützmacher H. Carreira EM. Angew. Chem. Int. Ed.  2008,  47:  4482 
• 2a Hayashi T. Ueyama K. Tokunaga N. Yoshida K.
  J. Am. Chem. Soc.  2003,  125:  11508 
• 2b Fischer C. Defieber C. Suzuki T. Carreira EM. J. Am. Chem. Soc.  2004,  126:  1628 
• 2c For a review, see: Glorius F. Angew. Chem. Int. Ed.  2004,  43:  3364 
• For reviews on allylation reactions, see:
• 3a Yamamoto Y. Asao N. Chem. Rev.  1993,  93:  2207 
• 3b Denmark SE. Fu J. Chem. Rev.  2003,  103:  2763 
• 3c Allylboration of carbonyl compounds: Lachance H. Hall DG. Org. React.  2009,  73:  1 
• 4 Barker TJ. Jarvo ER. Org. Lett.  2009,  11:  1047 
• Nucleophilic Ir(III)-catalyzed allylations of aldehydes with bisphosphine ligands:
• 5a Kim IS. Ngai M.-Y. Krische MJ. J. Am. Chem. Soc.  2008,  130:  14891 
• 5b Kim IS. Ngai M.-Y. Krische MJ. J. Am. Chem. Soc.  2008,  130:  6340 
• 5c Skucas E. Bower JF. Krische MJ. J. Am. Chem. Soc.  2007,  129:  12678 
• 5d Bower JF. Skucas E. Patman RL. Krische MJ. J. Am. Chem. Soc.  2007,  129:  15134 
• 5e Bower JF. Patman RL. Krische MJ. Org. Lett.  2008,  10:  1033 
• 7 Defieber C. Ariger MA. Moriel P. Carreira EM. Angew. Chem. Int. Ed.  2007,  46:  3139 
• 8 Defieber C. Paquin J.-F. Serna S. Carreira EM. Org. Lett.  2004,  6:  3873 
• Another alternative role for boric acid would be transmetalation with the allylboronate to form allylboronic acid, which should be more nucleophilic and a better transmetalating agent for iridium. See:
• 10a Brown HC. Racherla US. Pellechia PJ. J. Org. Chem.  1990,  55:  1868 
• 10b Zhao P. Incarbito CD. Hartwig JF. J. Am. Chem. Soc.  2007,  129:  1876 
• 11 Morrison DJ. Blackwell JM. Piers WE. Pure Appl. Chem.  2004,  76:  615 
• 12 Roush WR. Walts AE. Hoong LK. J. Am. Chem. Soc.  1985,  107:  8186 
• 13 Hansch C. Leo A. Taft RW. Chem. Rev.  1991,  91:  165 
• 14 van der Ent A. Onderdelinden AL. Inorg. Synth.  1990,  28:  90 
• 15 Ishiyama T. Ahiko T. Miyaura N. Tetrahedron Lett.  1996,  37:  6889 
• 16 For a review on the use of silver nitrate in chromatography, see: Williams CM. Mander LN. Tetrahedron  2001,  57:  425 
• 17 Schneider U. Kobayashi S. Angew. Chem. Int. Ed.  2007,  46:  5090 
• 18 Nobe Y. Arayama K. Urabe H. J. Am. Chem. Soc.  2005,  127:  18006 

6

No enantiomeric excess was observed in the products of the reactions with the chiral ligands in Table  [¹] .

9

An alternative role for boric acid would be to transmetalate with an iridium chloride precatalyst to form a more active iridium hydroxide complex. Iridium alkoxide complexes, e.g., [Ir(cod)OMe]₂, are competent catalysts for the reaction, consistent with this hypothesis.