Non-steric facial selectivity in nucleophilic 1,4-conjugate additions

Tetrahedron Letters

Volumn 38, Issue 3, 1997, Pages 425-428

  Okamoto, Iwao ^a   Ohwada, Tomohiko ^a   Shudo, Koichi ^a  

^a UNIVERSITY OF TOKYO   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

BICYCLO[2.2.2]OCTANE DERIVATIVE;

ARTICLE; DRUG SYNTHESIS; MOLECULAR DYNAMICS; REACTION ANALYSIS; STEREOCHEMISTRY;

EID: 0031032053     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(96)02316-7     Document Type: Article

References (19)

1. Trost, B. M., Fleming, I. Eds.; Semmelhack, M. F., Volume Ed. Comprehensive Organic Synthesis; Pergamon Press: Oxford, U.K., 1992; Vol. 4, Chapter 1.
2. Sato, M.; Murakami, M.; Sunami, S.; Kaneko, C.; Furuya, T.; Kurihara, H. J. Am. Chem. Soc., 1995, 117, 4279-4287.
3. Gung, B. W.; Francis, M. B. J. Org. Chem. 1993, 58, 6177-6179.
4. In general Michael reactions, involvement of cis/trans paths and their interconversion in the reaction make the analysis of mechanisms complicated. For example, see ref 1.
5. After the specified time, the volatile solvent and ethanethiol were distilled off with an argon flow, and the residue was flash-chromatographed to give the product mixture. In DMF and DMSO, the reaction mixture was poured into ether, and the organic layer was washed with dilute aqueous hydrochloric acid, dried over magnesium sulfate, and the solvent was evaporated and then the residue was flash-chromatographed.
6. a) A similar selectivity is observed for both 2-nitro and 3-nitro-9,10-dihydro-9,10-ethanoanthracen-11-ones in the reduction of sodium borohydride in a protic polar solvent, methanol. Ohwada, T.; Okamoto, I.; Haga, N.; Shudo, K. J. Org. Chem. 1994, 59, 3975-3984.
7. b) Haga, N.; Ohwada, T.; Okamoto I.; Shudo, K. Chem. Pharm. Bull., 1992, 40, 3349-3351.
8. a) Ohwada, T. J. Am. Chem. Soc., 1992, 114, 8818-8827.
9. b) Okamoto, I.; Ohwada, T.; Shudo, K. J. Org. Chem., 1996, 61, 3155-3166.
10. 9)
11. Cieplak, A. S. J. Am. Chem. Soc., 1981, 103, 4540-4552.
12. The thioethoxide anion is not externally solvated in these non-protic solvents, and is a strong nucleophile. See: Abramovitch, R. A.; Struble, D. L. Tetrahedron, 1968, 24, 357-380.
13. a) Nyquist, R. A.; Putzig, C. L.; Hasha, D. L. Appl. Spectrosc., 1989, 43, 1049-1053.
14. b) Nyquist, R. A.; Settineri, S. E. Appl. Spectrosc., 1991, 45, 1075-1084.
15. DMSO and DMF have higher acceptor ability than other solvents in terms of AN (acceptor number) values.: Gutmann, V. The Donor-Acceptor Approach to Molecular Interactions; Plenum: New York, 1978.
16. Wong, M. W.; Frisch, M. J; Wiberg, K. B. J. Am. Chem. Soc., 1991, 113, 4776-4782.
17. Houk, K. N.; Strozier, R. W. J. Am. Chem. Soc., 1973, 95, 4094-4096.
18. It is also possible to consider that the dipole moment of the transition structure of syn-addition is larger than that of anti-addition. However, this hypothesis can not account for the intrinsic syn-preference even in non-polar solvents.
19. One of the referees pointed out the possible predominant complex formation on the syn side of the ethanethiol prior to reagent attack because of a favorable electrostatic interaction and this will determine the facial selectivity. In this case, however, the nucleophile on the syn side is stabilized and less reactive, and therefore, the nucleophile would attack on the anti side.