Protecting group controlled stereoselective alkylation of asymmetrized bis(hydroxymethyl)propanoates (BHYMP*)

Tetrahedron Asymmetry

Volumn 10, Issue 3, 1999, Pages 439-447

  Banfi, Luca ^a   Guanti, Giuseppe ^a  

^a CNR   (Italy)

Author keywords

[No Author keywords available]

Indexed keywords

LITHIUM; METHYL GROUP; PROPIONIC ACID DERIVATIVE;

ALKYLATION; ARTICLE; CHELATION; CHEMICAL REACTION KINETICS; DIASTEREOISOMER; METHYLATION; PRIORITY JOURNAL; STEREOCHEMISTRY;

EID: 0033548136     PISSN: 09574166     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0957-4166(99)00006-3     Document Type: Article

References (21)

1. Associated to the National Institute of C.N.R. for the Chemistry of Biological Systems.
2. Banfi, L.; Basso, A.; Guanti, G.; Zannetti, M. T. Tetrahedron: Asymmetry 1997, 8, 4079-4088.
3. (a) Charlton, J. L.; Chee, G.-L. Can. J. Chem. 1997, 75, 1076-1083.
4. (b) Yoshida, S.; Yamanaka, T.; Miyake, T.; Moritani, Y.; Ohmizu, H.; Iwasaki, T. Tetrahedron 1997, 53, 9585-9598.
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6. Banfi, L.; Guanti, G. Eur. J. Org. Chem. 1998, 745-757 and references therein.
7. Previous results on the electrophilic attack on enolates of γ-alkoxyesters have been interpreted on the basis of a non-chelated enolate (Ref. 6). There is, however, an example (Ref. 7) of the alkylation of a δ-hydroxyester dianion, which was rationalized supposing a six-membered chelate involving the alkoxide and the double bond of the enolate.
8. (a) McGarvey, G. J.; Williams, J. M. J. Am. Chem. Soc. 1985, 107, 1435-1437.
9. (b) Hanessian, S.; Wang, W.; Gai, Y. Tetrahedron Lett. 1996, 37, 7473-7476.
10. (c) Hanessian, S.; Wang, W.; Gai, Y. Tetrahedron Lett. 1996, 37, 7477-7480.
11. Narasaka, K.; Ukaji, Y. Chem. Lett. 1986, 81-84.
12. (a) Ireland, R. E.; Wipf, P.; Armstrong III, J. D. J. Org. Chem. 1991, 56, 650-657.
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14. This assumption descends from the following observations: (a) for both 8a and 8b no unmethylated lactone was detected in the reaction mixture; (b) in the case of 8b (Table 2), the trans:cis ratio of lactones depended on the relative amount of lactones formed. When the quantity of lactones was higher, the percentage of cis lactone increased as well. If methylation occurred after cyclization, this ratio would have been independent from conversion, and the trans lactone would have most likely been the major diastereoisomer in any case. The absence of unmethylated lactone is moreover logical, since 8b is completely converted to the enolate and should have no tendency to undergo intramolecular attack by the alkoxide.
15. After reacting with MeI for 2 h between -78 °C and -50 °C, conversion was only 48% and the ratio 9-10:11-12 was 39:61. Moreover, a certain amount of desilylated products was detected.
16. (a) Fleming, I.; Lewis, J. J. J. Chem. Soc., Perkin Trans. 1 1992, 3257-3266 and following papers.
17. (b) Ref. 6a.
18. (c) Kahn, S. D.; Pau, C. F.; Chamberlin, A. R.; Hehre, W J. J. Am. Chem. Soc. 1987, 109, 650-663.
19. (d) Mohrig, J. R.; Rosenberg, R. E.; Apostol, J. W.; Bastienaansen, M.; Evans, J. W.; Franklin, S. J.; Frisbie, C. D.; Fu, S. S.; Hamm, M. L.; Hirose, C. B.; Hunstand, D. A.; James, T. L.; King, R. V.; Larson, C. J.; Latham, H. A.; Owen, D. A.; Stein, K. A.; Warnet, R. J. Am. Chem. Soc. 1997, 119, 479-486.
20. Although the two diastereomeric pairs 6a,7a and 9b,10b could not be separated, starting with compounds with different relative composition, we always observed a relationship between the diastereomeric ratios of the formed lactones with those of the acyclic precursors.
21. Force field calculations were performed with Chem3D Plus by CSC.