Free-Radical Cyclization of Bromoacetals. Use in the Construction of Bicyclic Acetals and Lactones

Journal of the American Chemical Society

Volumn 105, Issue 11, 1983, Pages 3741-3742

  Stork, Gilbert ^a   Mook, Robert ^a   Biller, Scott A ^a   Rychnovsky, Scott D ^a  

^a Och Spine at New York Presbyterian Hospitals   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 33845550427     PISSN: 00027863     EISSN: 15205126     Source Type: Journal    
DOI: 10.1021/ja00349a082     Document Type: Letter

References (16)

1. (a) Stork, G.; Baine, N.H. J. Am. Chem. Soc. 1982, 104, 2321. (b) Stork, G.; Mook, R., Jr. J. Am. Chem. Soc., in press, (c) Hart, D. J.; Tsai, Y.-M. J. Am. Chem. Soc. 1982, 104, 1430. (d) Hart, D. J.; Choi, J.-K.; Tsai, Y.-M. Tetrahedron Lett. 1982, 23, 4765.
2. Jacobus, J.; Leibner, J.E. J. Org. Chem. 1979, 44, 449.
3. The substances referred to in this paper were normally purified by flash chromatography with ethyl acetate-petroleum ether on silica gel.
4. The minor isomer was the cis isomer of 3, identical with the major product of the hydrogenation (cf. ref 5) of the 4-methyl derivative of the unsaturated lactone 4. The methyl and Ha resonances of the cis isomer were at δ 1.09 (d, J = 6.5 Hz) and 3.94 (dd, J = 4.8, 12.5 Hz).
5. Vigneron, J. P.; Meric, R.; Dhaenens, M. Tetrahedron Lett. 1980, 21, 2057.
6. Made by reaction of the disodium salt of ethynylisopropylcarbinol with carbon dioxide, followed by semihydrogenation.
7. Ueno, Y.; Chino, K.; Watanabe, M.; Moriya, O.; Okawara, M. J. Am. Chem. Soc. 1982, 104, 5564.
8. Some of our work on bromoacetal cyclizations was presented in a plenary lecture at the Fourth International Conference on Organic Synthesis, Tokyo, Aug 1982.
9. Bystrom, S.; Hogberg, H. E.; Norin, T. Tetrahedron 1981, 37, 2249. The NMR absorptions due to H, in the authentic cis- and trans-dimethyl lactones are very characteristic of their stereochemistry.
10. Rowlands, D. C.; Greenlee, K. W.; Derfer, J. M.; Boord, C.E. J. Org. Chem. 1952, 17, 807.
11. Conveniently made from 2-oxocyclohexaneacetic acid and L-Selec-tride. Cf.: Nicolaou, K. C.; Seitz, S. P.; Sipio, W. J.; Blount, J. F. J. Am. Chem. Soc. 1979, 101, 3884.
12. The hydroxy ester 10 was made by sodium borohydride-cerium trichloride reduction of the corresponding keto ester. The precyclization bromoacetal was made in this case from the dibromide derived from 2-chloroethyl vinyl ether, 1b The lactone 11 was then made by Jones oxidation at 0 °C.
13. Cf.: Hesse, R.H. Ado. Free Radical Chem. 1969, 3, 83.
14. In addition, two regioisomeric dimers of radical F were isolated in 9% yield. The amount of 1, 5-hydrogen transfer is thus between 16% and 28%, since some or all of the uncyclized isomer 14 could have arisen by direct hydrogen transfer from tri-n-butylstannane to radical E.
15. Baldwin, S. W.; Crimmins, M.T. Tetrahedron Lett. 1978, 4197. We thank these authors for a sample of lactone 16.
16. The (hydroxymethyl)cyclopentenecarboxyhc ester precursor of 17 was made from 3-(hydroxymethyl)cyclopentenecarboxaldehyde (Corey, E. J.; Danheiser, R.L. Tetrahedron Lett. 1973, 4477) by cyanide-catalyzed Mn02 oxidation (Corey, E. J.; Gilman, N. W.; Ganem, B. E. J. Am. Chem. Soc. 1968, 90, 5616).