Enantioselective addition of alcohols to ketenes catalyzed by a planar- chiral azaferrocene: Catalytic asymmetric synthesis of arylpropionic acids [21]

Journal of the American Chemical Society

Volumn 121, Issue 11, 1999, Pages 2637-2638

  Hodous, Brian L ^a   Ruble, J Craig ^a   Fu, Gregory C ^a  

^a MASSACHUSETTS INSTITUTE OF TECHNOLOGY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ALCOHOL; ARYLPROPIONIC ACID DERIVATIVE; FERROCENE DERIVATIVE; KETENE DERIVATIVE;

CATALYSIS; CATALYST; CHEMICAL REACTION; CHEMICAL STRUCTURE; CHIRALITY; ENANTIOMER; LETTER; STOICHIOMETRY; SYNTHESIS; TEMPERATURE SENSITIVITY;

EID: 0033599548     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja984021t     Document Type: Letter

References (24)

1. For reviews of routes to optically active arylpropionic acids, see: (a) Sonawane, H. R.; Bellur, N. S.; Ahuja, J. R.; Kulkarni, D. G. Tetrahedron: Asymmetry 1992, 3, 163-192. (b) Rieu, J.-P.; Boucherle, A.; Cousse, H.; Mouzin, G. Tetrahedron 1986, 42, 4095-4131.
2. For reviews of routes to optically active arylpropionic acids, see: (a) Sonawane, H. R.; Bellur, N. S.; Ahuja, J. R.; Kulkarni, D. G. Tetrahedron: Asymmetry 1992, 3, 163-192. (b) Rieu, J.-P.; Boucherle, A.; Cousse, H.; Mouzin, G. Tetrahedron 1986, 42, 4095-4131.
3. For example, see: (a) Jähme, J.; Rüchardt, C. Angew. Chem., Int. Ed. Engl. 1981, 20, 885-887. (b) Larsen, R. D.; Corley, E. G.; Davis, P.; Reider, P. J.; Grabowski, E. J. J. J. Am. Chem. Soc. 1989, 111, 7650-7651. (c) For related work involving thiols, see: Fehr, C.; Stempf, I.; Galindo, J. Angew. Chem., Int. Ed. Engl. 1993, 32, 1044-1046. For an overview, see: Fehr, C. Angew. Chem., Int. Ed. Engl. 1996, 35, 2566-2587.
4. For example, see: (a) Jähme, J.; Rüchardt, C. Angew. Chem., Int. Ed. Engl. 1981, 20, 885-887. (b) Larsen, R. D.; Corley, E. G.; Davis, P.; Reider, P. J.; Grabowski, E. J. J. J. Am. Chem. Soc. 1989, 111, 7650-7651. (c) For related work involving thiols, see: Fehr, C.; Stempf, I.; Galindo, J. Angew. Chem., Int. Ed. Engl. 1993, 32, 1044-1046. For an overview, see: Fehr, C. Angew. Chem., Int. Ed. Engl. 1996, 35, 2566-2587.
5. For example, see: (a) Jähme, J.; Rüchardt, C. Angew. Chem., Int. Ed. Engl. 1981, 20, 885-887. (b) Larsen, R. D.; Corley, E. G.; Davis, P.; Reider, P. J.; Grabowski, E. J. J. J. Am. Chem. Soc. 1989, 111, 7650-7651. (c) For related work involving thiols, see: Fehr, C.; Stempf, I.; Galindo, J. Angew. Chem., Int. Ed. Engl. 1993, 32, 1044-1046. For an overview, see: Fehr, C. Angew. Chem., Int. Ed. Engl. 1996, 35, 2566-2587.
6. For example, see: (a) Jähme, J.; Rüchardt, C. Angew. Chem., Int. Ed. Engl. 1981, 20, 885-887. (b) Larsen, R. D.; Corley, E. G.; Davis, P.; Reider, P. J.; Grabowski, E. J. J. J. Am. Chem. Soc. 1989, 111, 7650-7651. (c) For related work involving thiols, see: Fehr, C.; Stempf, I.; Galindo, J. Angew. Chem., Int. Ed. Engl. 1993, 32, 1044-1046. For an overview, see: Fehr, C. Angew. Chem., Int. Ed. Engl. 1996, 35, 2566-2587.
7. (a) Pracejus, H. Justus Liebigs Ann. Chem. 1960, 634, 9-22.
8. (b) Pracejus, H.; Kohi, G. Justus Liebigs Ann. Chem. 1969, 722, 1-11.
9. (c) Pracejus, H.; Tille, A. Chem. Ber. 1963, 96, 854-865.
10. (d) Pracejus, H.; Mätje, H. J. Prakt. Chem. 1964, 24, 195-205.
11. (e) For polymer-bound variants of the Pracejus catalyst, see: Yamashita, T.; Yasueda, H.; Nakamura, N. Bull. Chem. Soc. Jpn. 1979, 52, 2165-2166.
12. (a) Ruble, J. C.; Fu, G. C. J. Org. Chem. 1996, 61, 7230-7231.
13. (b) Ruble, J. C.; Latham, H. A.; Fu, G. C. J. Am. Chem. Soc. 1997, 119, 1492-1493.
14. (c) Ruble, J. C.; Tweddell, J.; Fu, G. C. J. Org. Chem. 1998, 63, 2794-2795.
15. Liang, J.; Ruble, J. C.; Fu, G. C. J. Org. Chem. 1998, 63, 3154-3155.
16. Ruble, J. C.; Fu, G. C. J. Am. Chem. Soc. 1998, 120, 11532-11533.
17. For a report of the N-acetylation of 2,3,4,5-tetramethyl-l-azaferrocene by acetyl chloride, see: Kuhn, N.: Schulten, M.; Zauder, E.; Augart, N.; Boese, R. Chem. Ber. 1989, 122, 1891-1896.
18. A pathway involving Brønsted-base catalysis is also possible. For a discussion of the mechanism of addition reactions to ketenes, see: (a) Tidwell, T. T. Ketenes; Wiley: New York, 1995; Chapter 5.5.1. (b) Andraos, J.; Kresge, A. J. J. Am. Chem. Soc. 1992, 114, 5643-5646. (c) Seikaly, H. R.; Tidwell, T. T. Tetrahedron 1986, 42, 2587-2613.
19. A pathway involving Brønsted-base catalysis is also possible. For a discussion of the mechanism of addition reactions to ketenes, see: (a) Tidwell, T. T. Ketenes; Wiley: New York, 1995; Chapter 5.5.1. (b) Andraos, J.; Kresge, A. J. J. Am. Chem. Soc. 1992, 114, 5643-5646. (c) Seikaly, H. R.; Tidwell, T. T. Tetrahedron 1986, 42, 2587-2613.
20. A pathway involving Brønsted-base catalysis is also possible. For a discussion of the mechanism of addition reactions to ketenes, see: (a) Tidwell, T. T. Ketenes; Wiley: New York, 1995; Chapter 5.5.1. (b) Andraos, J.; Kresge, A. J. J. Am. Chem. Soc. 1992, 114, 5643-5646. (c) Seikaly, H. R.; Tidwell, T. T. Tetrahedron 1986, 42, 2587-2613.
21. Interestingly, the enantioselectivity is a strong function of the counterion (triflate is the best of the several that we have screened).
22. 2).
23. 2, a solution of phenylmethylketene (45.0 mg. 0.341 mmol) in toluene (2.8 mL) was added by cannula to a -78 °C mixture of catalyst (+)-2c (13.7 mg, 0.034 mmol), 2,6-di-tert-butylpyridinium trifiate (14.0 mg, 0.041 mmol), and MeOH (20.7 μL, 0.511 mmol) in toluene (4.0 mL). The resulting homogeneous solution was stirred at -78 °C for 24 h, and then the reaction was quenched by the addition of n-propylamine (0.2 mL). The solvent was_removed by rotary evaporation, and the residue was immediately purified by flash chromatography (5% → 10% EtOAc/hexanes), which afforded 49.1 mg (88%) of a colorless liquid. For ee determination, the ester was reduced, trifluoroacetylated, and analyzed by GC (Chiraldex G-TA), which revealed a 77% ee.
24. We have observed analogous behavior with other arylalkylketenes.