Substituent effects on intramolecular dipolar cycloadditions: The gem-dicarboalkoxy effect

Tetrahedron Letters

Volumn 37, Issue 4, 1996, Pages 451-454

  Jung, Michael E ^a   Vu, Binh T ^a  

^a UNIVERSITY OF CALIFORNIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CYCLOPENTANE DERIVATIVE; OXAZOLIDINE DERIVATIVE;

ARTICLE; DRUG SYNTHESIS; REACTION ANALYSIS; STEREOCHEMISTRY;

EID: 0030031640     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/0040-4039(95)02196-5     Document Type: Article

References (20)

1. American Chemical Society Arthur C. Cope Scholar, 1995.
2. Jung, M. E.; Gervay, J. J. Am. Chem. Soc. 1991, 113, 224.
3. There is some confusion about the meaning of the term "reactive rotamer effect." For an explanation of what we mean by the term, see: Jung, M. E. Synlett 1990, 186.
4. For another interpretation of the reasons behind the gem-dialkyl effect, see: Parrill, A. L.; Dolata, D. P. Tetrahedron Lett. 1994, 35, 7319.
5. Jung, M. E.; Trifunovich, I. D.; Lensen, N. Tetrahedron Lett. 1992, 33, 6719.
6. Copper-catalyzed addition of allylmagnesium halide to ethylidene, isopropylidene, cyclopentylidene, or benzylidene malonate followed by decarbomethoxylation and reduction furnished 1b-e. Alkylation of dimethyl allylmalonate with chloroacetaldehyde oxime afforded 1f. The monoester 1g was prepared by allylation of γ-butyrolactone, opening with methoxide and conversion of the alcohol to the aldoxime via the aldehyde. Alkylation of allyldithiane with bromoacetal followed by conversion of the acetal to the aldoxime via the aldehyde gave 1h.
7. Conversion of hexanal oxime to the saturated nitrile oxide showed that the formation of the nitrile oxide is fast with respect to dimerization so that the calculated half-lives accurately measure the relative rates of cyclizations.
8. a) Grundmann, C.; Grünanger, P. The Nitrile Oxides. 1971, Springer-Verlag, New York,
9. b) Caramella, P.; Grünanger, P. 1,3-Dipolar Cycloaddition. 1984, Vol. 1, Padwa, A., Ed.; John Wiley & Sons, New York, pp. 291-392.
10. c) Curran, D. P. Advances in Cycloaddition. 1988, JAI Press, Greenwich, CT, Vol. 1, p. 150.
11. Just, G.; Dahl, K. Tetrahedron 1968, 24, 5251.
12. Brown, F. K.; Raimondi, L.; Wu, Y.-D.; Houk, K. N. Tetrahedron Lett. 1992, 33, 4405.
13. This effect may well have been seen before but not measured. For example, Parker reported the intramolecular Diels-Alder reaction of an olefinic furan having a gem-dicarboalkoxy group but does not mention whether the simple hydrocarbon (without the ester groups) cyclized or not Parker, K. A.; Adamchuk, M. R. Tetrahedron Lett. 1978, 1689.
14. For an early example of the gem-dialkoxy and gem-dithioalkoxy effects, see: Sternbach, D. D.; Rosanna, D. M; Onan, K. D. Tetrahedron Lett. 1985, 26, 591.
15. Kim, H. R.; Kim, H. J.; Duffy, J. L.; Olmstead, M. M.; Ruhlandt-Senge, K.; Kurth, M. J. Tetrahedron Lett. 1991, 32, 4259.
16. Kurth and coworkers carried out the cyclization at 25 °C. In our hands, the diastereoselectivity does not change at this temperature, still favoring 3b over 3b′ by about 6.5:1.
17. Private communication. Houk, K. N.; Raimondi, L. For a description of the force field used in these calculations of transition structures for nitrile oxide cyclizations, see: Brown, F. K.; Raimondi, L.; Wu, Y.-D.; Houk, K. N. Tetrahedron Lett. 1992, 33, 4405.
18. Kozikowski, A. P.; Adamczyk, M. Tetrahedron Lett. 1982, 25, 3123.
19. Stothers, J. B.; Tan, C. T. Can. J. Chem. 1974, 52, 308. In the eis isomer 4b, the peaks assigned to the methyl and hydroxymethyl carbons were both upfield by ∼ 0.65 ppm of the corresponding peaks in the trans isomer 4b′ due to the shielding effect. The structures of the isomeric pairs 3e/3e′ and 3g/3g′ were assigned by analogy.
20. The gem-bis(phenylsulfonyl) analogue gave 5 in 50-60% yield under the normal reaction conditions. We assumed that this compound is formed via cyclization of the bis-sulfonyl nitrile oxide which then loses an equivalent of phenylsulfmic acid in the presence of base to give 5. matrix presented