Conservation of absolute configuration in the acyclic rhodium-catalyzed allylic alkylation reaction: Evidence for an Enyl (σ + π) organorhodium intermediate

Journal of the American Chemical Society

Volumn 120, Issue 22, 1998, Pages 5581-5582

  Evans, P Andrew ^a   Nelson, Jade D ^a  

^a UNIVERSITY OF DELAWARE   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ORGANOMETALLIC COMPOUND; RHODIUM;

ALKYLATION; CATALYSIS; CHEMICAL BINDING; COMPLEX FORMATION; LETTER;

EID: 0032503512     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja980030q     Document Type: Article

References (22)

1. For a recent review on the transition metal-catalyzed allylic alkylation, see: Trost, B. M.; Van Vranken, D. L. Chem. Rev. 1996, 96, 395 and pertinent references therein.
2. For lead references on other transition metal-catalyzed allylic alkylation reactions: see (a) Co: Bhatia, B.; Reddy, M. M.; Iqbal, J. Tetrahedron Lett. 1993,34,6301.
3. (b) Fe: Xu, Y.; Zhou, B. J. Org. Chem. 1987, 52, 974.
4. (c) Ir: Takeuchi, R.; Kashio, M. Angew. Chem., Int. Ed. Engl. 1997, 36, 263.
5. (d) Mo: Ward, Y. D.; Villanueva, L. A.; Allred, G. D.; Liebeskind, L. S. J. Am. Chem. Soc. 1996, 118, 897.
6. (e) Ni: Bricout, H.; Carpentier, J.-F.; Mortreux, A. J Chem. Soc., Chem. Commun. 1995, 1863.
7. (f) Pt: Brown, J. M.; McIntyre, J. E. J. Chem. Soc., Perkin Trans. 2 1985, 961.
8. (g) Ru: Kondo, T.; Ono, H.; Satake, N.; Mitsudo, T.; Watanabe, Y. Organometallics 1995, 14, 1945.
9. (h) W: Lloyd-Jones, G. C.; Pfalz, A. Angew. Chem., Int. Ed. Engl. 1995, 34, 462 and pertinent references therein.
10. For the first example of a Rh-catalyzed allylic alkylation, see: Tsuji, J.; Minami, I.; Shimizu, I. Tetrahedron Lett. 1984, 25, 5157.
11. Minami, I.; Shimizu, I.; Tsuji, J. J. Organomet. Chem. 1985, 296, 269. We are not aware of any other reports of Rh-catalyzed allylic alkylations.
12. Evans, P. A.; Nelson, J. D. Tetrahedron Lett. 1998, 38, 1725.
13. 6c crystallography.
14. (a) Sharp P. R. In Comprehensive Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon Press: New York, 1995; Chapter 2, p 272.
15. (b) Lawson, D. N.; Osborn, J. A.; Wilkinson, G. J. Chem. Soc. A 1966, 1733.
16. Tanaka, I.; Jin-no, N.; Kushida, T.; Tsutsui, N.; Ashida, T.; Suzuki, H.; Sakurai, H.; Moro-oka, Y.; Ikawa, T. Bull. Chem. Soc. Jpn. 1983, 56, 657 and pertinent references therein.
17. 2c However, treatment of the deuterium-labeled allylic carbonate 6 under the reported reaction conditions furnished the allylic alkylation products 7a/b in modest yield as a 2:1 mixture of regioisomers.
18. Treatment of both the isomeric allylic carbonates 8a/b under analogous conditions in the presence of a catalytic amount of Pd(PPh3)4 furnished 9a as the major product (≥ 19:1) in both cases. Hence, if the rhodium reaction was proceeding through a π-allyl type intermediate, 9a would be expected vide infra.
19. For an example of double inversion to give net retention of stereochemistry, see: Faller, J. W.; Linebarrier, D. Organometallics 1988, 7,1670.
20. The other enantiomer is presumably the result of isomerization of the organorhodium intermediate leading to alkylation from the other end of the allylic system.
21. 4), filtered, and concentrated in vacuo to afford a crude oil. Purification by flash chromatography (eluting with 9:1 dichloromethane/pentane) furnished the allylic alkylation product 11 (80.9 mg, 86%) as a colorless oil, with 95% enantiomeric excess by capillary GC analysis with a Chiraldex TFA column.
22. N2 type process is unlikely based on the observation that increased alkene substitution in a series of primary carbonates leads to decreased reactivity, as illustrated below. Matrix equation presented