Titanium fluoride complexes as catalysts for the enantioselective addition of Me3Al to aldehydes

Tetrahedron Letters

Volumn 39, Issue 52, 1998, Pages 9593-9596

  Pagenkopf, Brian L ^a   Carreira, Erick M ^a  

^a California Institute of Technology   (United States)

Author keywords

Alkylation; Asymmetric induction; Fluorine; Titanium

Indexed keywords

ALDEHYDE; ALUMINUM DERIVATIVE; HETEROCYCLIC COMPOUND; TITANIUM DERIVATIVE; TITANIUM FLUORIDE; UNCLASSIFIED DRUG;

ARTICLE; CATALYST; COMPLEX FORMATION; DRUG ISOLATION; ENANTIOMER; TRIMETHYLALUMINUM;

EID: 0032564559     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(98)02332-6     Document Type: Article

References (29)

1. 1. (a) Knochel, P.; Perea, J. J. A.; Jones, P. Tetrahedron 1998, 54, 8275.
2. (b) Kitamura, M.; Yamakawa, M.; Oka, H.; Suga, S.; Noyori, R. Chem. Eur. J. 1996, 2, 1173.
3. (c) Seebach, D.; Beck, A. K.; Schmidt, B.; Wang, Y. M. Tetrahedron 1994, 50, 4363.
4. (d) Soal, K.; Niwa, S. Chem. Rev. 1992, 92, 833.
5. (e) Noyori, R.; Kitamura, M. Angew. Chem., Int. Ed. Engl. 1991, 30, 49.
6. (f) For a recent lead reference for diethylzinc additions, see: Qui, J.; Guo, C.; Zhang, X. J. Org. Chem. 1997, 62, 2665.
7. 2. Nowotny, S.; Vettel, S.; Knochel, P. Tetrahedron Lett. 1994, 35, 4539.
8. 2Zn addition to 3-trimethylsilyl-2-propynal: Oguni, N.; Satoh, N.; Fujii, H. Synlett 1995, 1043.
9. 2Zn additions to metallocenecarboxaldehydes: Watanabe, M. Synlett 1995, 1050 and references therein.
10. (c) Rijnberg, E.; Hovestad, N. J.; Kleij, A. W.; Jastrzebski, J. T. B. H.; Boersma, J.; Janssen, M. D.; Spek, A. L.; van Koten, G. Organometallics 1997, 16, 2847. For mechanistic studies on dimethylzinc additions, see reference 1 (a).
11. 3: Ito, Y. N.; Ariza, X.; Beck, A. K.; Andrej, B.; Camille, G.; Gawley, R. E.; Kuhnle, F. N. M.; Tuleja, J.; Wang, Y. M.; Seebach, D. Helv. Chim. Acta 1994, 77, 2071.
12. 3Al: Chan, A. S. C.; Zhang, F.-Y.; Yip, C.-W. J. Am. Chem. Soc. 1997, 119, 4080.
13. 6. (a) Gauthier, D.; Carreira, E. M. Angew. Chem., Int. Ed. Engl. 1996, 35, 2363.
14. (b) Pagenkopf, B. L.; Krüger, J.; Stojanovic, A.; Carreira, E. M. Angew. Chem., Int. Ed. Engl. in press.
15. 7. For recent reviews on transition metal fluorides, see: (a) Murphy, E. F.; Murugavel, R.; Roesky, H. W. Chem. Rev. 1997, 97, 3425, and references therein.
16. (b) Doherty, N. M.; Hoffman, N. W. Chem. Rev. 1991, 91, 553.
17. 8. Ashby, E. C.; Noding, S. A. J. Org. Chem. 1979, 44, 4792. For an in-depth discussion of such transition-state structures, see: Evans, D. A. Science 1988, 240, 4851.
18. 8. Ashby, E. C.; Noding, S. A. J. Org. Chem. 1979, 44, 4792. For an in-depth discussion of such transition-state structures, see: Evans, D. A. Science 1988, 240, 4851.
19. 9. Ziemkowska, W.; Pasynkiewicz, S.; Glowiak, T. J. Organomet. Chem. 1998, 562, 3.
20. 1H NMR spectroscopy we have observed the presence of numerous methyl signals consistent with the presence of species containing the Me-Al bond. Further specroscopic studies are warranted that will allow for characterization of the observed species.
21. 4 which gives colorless and homogeneous solutions in MeCN. No difference in % ee was observed with either stock solution.
22. 12. Preparations of TADDOL Ti(IV) complexes: Haase, C.; Sarko, C. R.; Dimare, M. J. Org. Chem. 1995, 60, 1777.
23. 3CN, 0.135 mL) was added, and the reaction mixture was stirred for an additional 20 min. The resulting solution was cooled to -10 °C and benzaldehyde was added neat (0.5 mmol, 0.051 mL). After stirring for 12 h at -10 °C, the flask was transferred to a 0 °C ice bath and allowed to gradually warm to room temperature. The reaction mixture was quenched by transfer of the solution into 5 mL of ice cold 10% aqueous sulfuric acid and then extracted with diethyl ether. Purification by chromatography on silica gel afforded the alcohol. The ligand may be recovered quantitatively without racemization.
24. 14. Optically active trans-1,2-cyclohexane dicarboxylic acid is obtained from enzymatic hydrolysis of the corresponding cis-diester or by resolution of the trans-diacid with (S)-(-)-α-methylbenzylamine. (a) Kobayashi, S.; Kamiyama, K.; Ohno, M. Chem. Pharm. Bull. 1990, 38, 350.
25. (b) Longeau, A.; Durand, S.; Spiegel, A.; Knöchel, P. Tetrahedron Asym. 1997, 8, 987.
26. (c) Applequist, D. E.; Werner, N. J. Org. Chem. 1963, 25, 48.
27. 15. The enantioselectivity of the addition reaction displays only modest sensitivity to temperature. Thus, at -20 °C and 0 °C sec-phenethyl alcohol was isolated in 85 and 82% ee, respectively; when the addition was conducted at room temperature a further drop to 79% ee was observed. At -78 °C, the reaction rate becomes too slow to be preparatively useful.
28. 16. Kabbara, J.; Flemming, S.; Nickisch, K.; Neh, H.; Westermann, J. Synlett 1994, 679.
29. 3Al to benzaldehyde consistently gave high % ee's. We are investigating these observations along with developing modified conditions that will expand the scope of the process; these results will be reported in the future.