New insights into the classic chiral Grignard reagent (1R,2S,5R)- menthylmagnesium chloride

Angewandte Chemie - International Edition

Volumn 45, Issue 39, 2006, Pages 6509-6512

  Beckmann, Jens ^b   Dakternieks, Dainis ^a   Dräger, Martin ^c   Duthie, Andrew ^a  

^a DEAKIN UNIVERSITY   (Australia)

^b FREIE UNIVERSITÄT BERLIN   (Germany)

^c JOHANNES GUTENBERG UNIVERSITY   (Germany)

Author keywords

Asymmetric synthesis; Chiral Grignard reagents; Grignard reaction; Kinetics

Indexed keywords

ASYMMETRIC SYNTHESIS; CHIRAL GRIGNARD REAGENTS; GRIGNARD REACTIONS; KINETICS;

MAGNESIUM COMPOUNDS; MIXTURES; REACTION KINETICS;

STEREOCHEMISTRY;

EID: 33749869312     PISSN: 14337851     EISSN: None     Source Type: Journal    
DOI: 10.1002/anie.200602091     Document Type: Article

References (21)

1. The substituent names menthyl (Men) and neomenthyl (Neom) stand for the (1R,2S,5R)- and the (1S,2S,5R)-2-isopropyl-5-methylcyclohexyl group, respectively.
2. "Asymmetric Free-Radical Reductions Mediated by Chiral Stannanes, Germanes and Silanes": J. Beckmann, D. Dakternieks, C. H. Schiesser in Handbook of Chiral Chemicals (Ed.: D. Ager), Marcel Dekker, New York, 2005, chap. 27, pp. 531-538.
3. M. Tanaka, I. Ogata, Bull. Chem. Soc. Jpn. 1975, 48, 1094.
4. a) H. Schumann, B. C. Wassermann, J. Organomet. Chem. 1989, 365, C1;
5. b) H. Schumann, B. C. Wassermann, F. E. Hahn, Organometallics 1992, 11, 2803.
6. [7]
7. H. M. Walborsky, A. E. Young, J. Am. Chem. Soc. 1964, 86, 3288.
8. R. W. Hoffmann, Chem. Soc. Rev. 2003, 32, 225, and references therein.
9. J. D. Morrison, W. F. Masler, J. Org. Chem. 1974, 39, 270.
10. D. Dakternieks, K. Dunn, D. J. Henry, C. H. Schiesser, E. R. T. Tiekink, Organometallics 1999, 18, 3342.
11. C. Lucas, C. C. Santini, M. Prinz, M.-A. Cordonnier, J.-M. Basset, M.-F. Connil, B. Jousseaume, J. Organomet. Chem. 1996, 520, 101.
12. D. Dakternieks, K. Dunn, B. R. Vincent, E. R. T. Tiekink, Main Group Met. Chem. 2000, 23, 329.
13. [13]
14. "Wet Analysis of Grignard Reagents": G. S. Silverman in Handbook of Grignard Reagents (Eds.: G. S. Silverman, P. E. Rakita), Marcel Dekker, New York, 1996, chap. 6, 89-92.
15. D. H. R. Barton, Experientia 1950, 6, 316.
16. P. Sykes, A Guidebook to Mechanism in Organic Chemistry, 6th ed., Longman Scientific & Technical, 1986, chap. 8, pp. 221-223. The reaction involves a concerted polar mechanism via a six-membered cyclic transition state in which two molecules of RMgX are implicated. The second molecule of RMgX acts as a Lewis catalyst.
17. The optical rotations of isolated 1 and 2 suggest that the material described in Ref. [6] was actually a mixture of 1 and 2, with a ratio of approximately 54:46.
18. 2SnCl (5) (ClRMg→Cl-Sn) and as a basic catalyst towards the other moiety of 5 (RMgCl→Sn). The resulting stannyl anion carried out a nucleophilic attack at the axial site of the activated 5 (formally reductive elimination). This competitive reaction was favored by the reduced polarity of the solvent, which had been chosen to slow down the attack of the unwanted Neom carbanion.
19. 119Sn NMR signals (total integral value of approximately 6%) were observed and remain unassigned.
20. [20] and then into 6 by base hydrolysis to confirm the assignment of these signals from the NMR spectrum.
21. B. Zobel, A. E. K. Lim, K. Dunn, D. Dakternieks, Organometallics 1999, 18, 4889.