Umpolung of Michael acceptors catalyzed by N-heterocyclic carbenes

Journal of the American Chemical Society

Volumn 128, Issue 5, 2006, Pages 1472-1473

  Fischer, Christian ^a   Smith, Sean W ^a   Powell, David A ^a   Fu, Gregory C ^a  

^a MASSACHUSETTS INSTITUTE OF TECHNOLOGY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CARBENE; HETEROCYCLIC COMPOUND;

ARTICLE; BAYLIS HILLMAN REACTION; CATALYSIS; CYCLIZATION; HECK REACTION; HYPOTHESIS; MICHAEL ADDITION; MOLECULAR INTERACTION; STOICHIOMETRY;

ALKENES; ALKYLATION; CATALYSIS; CYCLIZATION; HETEROCYCLIC COMPOUNDS; HYDROCARBONS; HYDROCARBONS, CYCLIC; METHANE;

EID: 32244441382     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja058222q     Document Type: Article

References (19)

1. For leading references, see: Powell, D. A.; Maki, T.; Fu, G. C. J. Am. Chem. Soc. 2005, 127, 510-511.
2. For overviews of processes catalyzed by nucleophilic carbenes, see: (a) Zeitler, K. Angew. Chem., Int. Ed. 2005, 44, 7506-7510.
3. (b) Nair, V.; Bindu, S.; Sreekumar, V. Angew. Chem., Int. Ed. 2004, 43, 5130-5135.
4. For a review of processes catalyzed by nucleophilic phosphines, see: Methot, J. L.; Roush, W. R. Adv. Synth. Catal. 2004, 346, 1035-1050.
5. For precedent in a more highly activated substrate, see: Enders, D.; Breuer, K.; Teles, J. H.; Ebel, K. J. Prakt. Chem. 1997, 339, 397-399.
6. (a) Seebach, D. Angew. Chem., Int. Ed. Engl. 1979, 18, 239-258.
7. (b) Umpoled Synthons; Hase, T. A., Ed.; Wiley: New York, 1987.
8. For pioneering studies wherein addition of a catalyst to the carbonyl carbon of an α,β-unsaturated aldehyde, followed by deprotonation of the aldehyde proton, leads to nucleophilicity at the β position, see: (a) Burstein, C.; Glorius, F. Angew. Chem., Int. Ed. 2004, 43, 6205-6208.
9. (b) Sohn, S. S.; Rosen, E. L.; Bode, J. W. J. Am. Chem. Soc. 2004, 126, 14370-14371. Of course, this approach can be applied to α,β- unsaturated aldehydes but not to esters, amides, or nitriles.
10. For leading references, see: Basavaiah, D.; Rao, A. J.; Satyanarayana, T. Chem. Rev. 2003, 103, 811-892.
11. 3: Gong, J. H.; Im, Y. J.; Lee, K. Y.; Kim, J. N. Tetrahedron Lett. 2002, 43, 1247-1251.
12. (a) Krafft, M. E.; Haxell, T. F. N. J. Am. Chem. Soc. 2005, 127, 10168-10169.
13. (b) Krafft, M. E.; Seibert, K. A.; Maxell, T. F. N.; Hirosawa, C. Chem. Commun. 2005, 5772-5774.
14. For reports of the parent carbene (Ar = Ph), see: (a) Enders, D.; Breuer, K.; Raabe, G.; Runsink, J.; Teles, J. H.; Melder, J.-P.; Ebel, K.; Brode, S. Angew. Chem., Int. Ed. Engl. 1995, 34, 1021-1023.
15. (b) Enders, D.; Balensiefer, T. Acc. Chem. Res. 2004, 37, 534-541.
16. (c) See also: Walentowski, R.; Wanzlick, H.-W. Z. Naturforsch., B: Chem. Sci. 1970, 25, 1421-1423.
17. For an early study of electronic effects on a process catalyzed by nucleophilic triazole-derived carbenes, see: Teles, J. H.; Melder, J.-P.; Ebel, K.; Schneider, R.; Gehrer, E.; Harder, W.; Brode, S.; Enders, D.; Breuer, K.; Raabe, G. Helv. Chim. Acta 1996, 79, 61-83.
18. Notes: (a) An α,β-unsaturated phenyl ketone can be cyclized, but a significant amount of the β,γ-unsaturated enone is produced. (b) We have not yet been able to achieve efficient seven-membered ring formation or mfermolecular β-alkylation. (c) Substrates in which the olefin has a Z, rather than an E, configuration cyclize less rapidly. (d) Under our standard conditions, we have not been able to effectively cyclize α-substituted enoates.
19. In a competition experiment between the alkyl bromide and the alkyl chloride illustrated in entries 1 and 3 of Table 2, comparable reaction rates were observed, consistent with the hypothesis that cyclization may not be the turnover-limiting step for these substrates. In contrast, for the homologous substrates (six-membered ring formation), the chloride is essentially unreactive under the conditions in which the bromide cyclizes.