Long-range asymmetric induction by conjugate addition to alkenylcyclohexadienyliron complexes

Tetrahedron Letters

Volumn 37, Issue 50, 1996, Pages 9009-9012

  Hudson, Richard D A ^a   Osborne, Simon A ^b   Roberts, Edward ^b   Stephenson, G Richard ^a  

^a UNIVERSITY OF EAST ANGLIA   (United Kingdom)

^b NEUROSCIENCE RESEARCH CENTRE   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

ALKENE DERIVATIVE; IRON COMPLEX;

ARTICLE; CHEMICAL REACTION; CONJUGATION; DIASTEREOISOMER; DRUG SYNTHESIS; REACTION ANALYSIS; STEREOCHEMISTRY; STEREOISOMERISM;

EID: 0010371563     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(96)02115-6     Document Type: Article

References (18)

1. 1. For a review of conjugate addition to α,β-unsaturated ketones and esters, see: Patai, S. and Rappoport, Z. The chemistry of enones, pt1, Wiley, New York, 1989; pp. 281-315 and 355-469.
2. 2. Stephenson, G. R.; Voyle, M.; Williams, S. Tetrahedron Lett., 1990, 31, 3979.
3. 3. Dunn, M. J.; Jackson, R. F. W.; Stephenson, G. R. Synlett, 1992, 905.
4. 4. Stephenson, G. R.; Finch, H.; Owen, D. A.; Swanson, S. Tetrahedron, 1993, 49, 5649.
5. 5. Malkov, A. V.; Stephenson, G. R. J. Organometal. Chem., 1995, 489, C44.
6. 6. We prepare this complex in 2 g batches; since it is less stable than typical tricarbonyl(cyclohexadienyl)iron salts, it should be used soon after preparation.
7. 7. Bernasconi, C. F. Tetrahedron, 1989, 45, 4017.
8. 8. A typical procedure involves the preparation of the required organocuprate (2 eq.) from commercially available phenyl or butyllithium with copper bromide dimethyl sulphide complex at -30°C in THF. This is followed by cooling to -78°C and addition of the vinyl-extended organoiron salt (1 eq.) in one portion as a dry powder. Once the dienyl complex has been consumed (IR), aqueous workup with sat. ammonium chloride is followed by purification by column chromatography on silica gel.
9. 5 portion of the ligand, but is aligned opposite (s-trans) to the horseshoe of the dienyl system and tilted slightly up towards the cyclohexadienyl C-6 methylene group.
10. 10. Adams, C. M.; Andreas, H.; Koller, M.; Marcuzzi, A.; Prewo, R.; Solana, I.; Vincent, B.; von Philipsborn, W. Helv. Chim. Acta, 1989, 22, 1658.
11. 11. D. M. F. Manon, University of Bath, unpublished results.
12. 12. Related conjugate addition steps are known for organochromium arene complexes, but the stereocontrol leading to the E isomer of the exocyclic double bond is particular to the work described here. For examples of organochromium mediated conjugate addition, see: Semmelhack, M. F.; Suefert, W.; Keller, L. J. Am. Chem. Soc., 1980, 102, 6584; Uemura, M.; Minami, T.; Hayashi, Y. J. Organometal. Chem., 1986, 299, 119.
13. 12. Related conjugate addition steps are known for organochromium arene complexes, but the stereocontrol leading to the E isomer of the exocyclic double bond is particular to the work described here. For examples of organochromium mediated conjugate addition, see: Semmelhack, M. F.; Suefert, W.; Keller, L. J. Am. Chem. Soc., 1980, 102, 6584; Uemura, M.; Minami, T.; Hayashi, Y. J. Organometal. Chem., 1986, 299, 119.
14. 13. Stephenson, G. R.; Astley, S. T. Synlett, (1992), 507.
15. 14. Stephenson, G. R.; Astley, S. T.; Palotai, I. M.; Howard, P. W.; Owen, D. A.; Williams, S. Regiocontrolled Application of Transition Metal π-complexes. In Organic Synthesis via Organometallics; Dötz, K. H.; Hoffmann, R. W. Eds.; Vieweg, Braunschweig 1991, 169.
16. 15. Stephenson, G. R.; in Advanced Asymmetric Synthesis, Chapter 16, Blackie, London, 1996, 313.
17. 16. Howell, J. A. S.; Thomas, M. J. J. Organometal. Chem., 1983, 247, C21.
18. 17. Pearson, A. J.; Synlett, 1990, 10.