On the carbocyclization of ω-styrenylbenzyllithiums

Synlett

Volumn , Issue 7, 1999, Pages 1142-1144

  Krief, Alain ^a   Remacle, Bruno ^a   Dumont, Willy ^a  

^a UNIVERSITY OF NAMUR   (Belgium)

Author keywords

Arylcyclopentanes; Benzyllithiums; Carbocyclisation; Diastereoselection

Indexed keywords

BENZYL DERIVATIVE; CYCLOPENTANE DERIVATIVE; LITHIUM DERIVATIVE; STYRENE DERIVATIVE;

ARTICLE; CHEMICAL REACTION KINETICS; CYCLIZATION; DIASTEREOISOMER; LOW TEMPERATURE PROCEDURES; REACTION ANALYSIS; SYNTHESIS; TEMPERATURE DEPENDENCE;

EID: 0032776864     PISSN: 09365214     EISSN: None     Source Type: Journal    
DOI: 10.1055/s-1999-5733     Document Type: Article

References (14)

1. (a) Krief, A.; Barbeaux, P. J. Chem. Soc. Chem. Commun. 1987, 16, 1214-1216;
2. (b) Krief, A.; Kenda, B.; Remacle, B. Tetrahedron 1996, 52, 7435-7463;
3. (c) Krief, A.; Kenda, B.; Barbeaux, P.; Guittet, E. Tetrahedron 1994, 50, 7177-7192.
4. Comparatively the cyclization of 2a in ether is very slow at -78 æC. The presence of the phenyl group on the C,C double bond enhances dramatically the rate of the reaction in that solvent.
5. For related reactions producing benzyllithiums after carbocyclization (a) Wei, X.; Taylor, R.J.K. Tetrahedron Lett. 1997, 38, 6467;
6. (b) Woltering, M.J.; Frölich, R.; Hoppe, D. Angew. Chem. Int. Ed. Engl. 1997, 36, 1764;
7. (c)Tomooka, K.; Komine, N.; Sasaki, T.; Shimizu, H.; Nakai, T. Tetrahedron Lett. 1998, 39, 9715
8. (d) Bailey, W.F.; Gavaskar, K.V. Tetrahedron 1994, 50, 5957.
9. These reactions have been carried out with (a) 1.6 N n-BuLi in hexanes; (b) 1.3 N s-BuLi in cyclohexane or (c) 1.7 N t-BuLi in pentane all from the Aldrich Company.
10. For example when the reaction is carried out with s-BuLi in ether at -45 °C on a 50/50 or a 10/90 (Table, entry d) ratio of Z-1d/E-1d we obtained a 88/12 or a 90/10 ratio of 4′d/4″d. For a related result see : Hoffmann, R.W.; Koberstein, R.; Remacle, B.; Krief, A. Chem. Commun. 1997, 2189-2190.
11. 3″d is usually produced when the carbocyclization is performed in THF. Using the strategy disclosed in this section we have been able to generate instead 3′d in the same solvent.
12. Cyclization of 2d in pentane at 20 °C leads to a diastereoisomeric mixture of 4′d and 4″d after methanolysis.
13. (a) Bailey, W. F.; Carson, M. W. J. Org. Chem. 1998, 63, 361;
14. (b) Coldham, I.; Hufton, R. Tetrahedron. 1996, 52, 12541.