Intramolecular cationic cyclizations initiated by electrocyclic cleavage of cyclopropanes. Synthesis of trienic cyclopentane derivatives

Tetrahedron Letters

Volumn 37, Issue 4, 1996, Pages 439-442

  Gassman, Paul G ^a   Tan, Lushi ^a   Hoye, Thomas R ^a  

^a University of Minnesota   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CYCLOPENTANE DERIVATIVE;

ARTICLE; DRUG SYNTHESIS; REACTION ANALYSIS;

EID: 0030058852     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/0040-4039(95)02213-9     Document Type: Article

References (13)

1. For a review see Sorenson, T. S.; Rauk, A. in "Pericyclic Reactions", vol. II, Marchand, A. P.; Lehr, R. E. Ed., Academic Press, New York, 1977, 1.
2. (a) Sasaki, T.; Eguchi, S; Kiriyama, T. J. Org. Chem. 1973, 38, 2230.
3. (b) Danheiser, R. L.; Morin, J. M.; Basak, M. Y. A. Tetrahedron Lett. 1981, 22, 4205.
4. (c) Banwell, M. G.; Wu, A. W. J. Chem. Soc., Perkin Trans. 1994, 1, 2671.
5. (a) Gassman, P. G.; Singleton, D. A. J. Am. Chem. Soc. 1984, 106, 6085.
6. (b) Gassman, P. G.; Singleton, D. A. J. Org. Chem. 1986, 51, 3075.
7. (c) Gassman, P. G.; Riehle, R. J. J. Am. Chem. Soc. 1989, 111, 2319.
8. (d) Gorman, D. B.; Gassman, P. G. J. Org. Chem. 1995, 60, 977.
9. (a) Gassman, P. G.; Singleton, D. A.; Wilwerding, J. J.; Chavan, S. P. J. Am. Chem. Soc. 1987, 109, 2182.
10. (b) Gassman, P. G.; Chavan, S. P. J. Org. Chem. 1988, 53, 2392.
11. 6b of cyclopentene followed by a lithium-salt-free Wittig reaction with ethylidenetriphenylphosphorane, generated in situ from ethyltriphenylphosphonium bromide and sodium tert-butoxide, gave (Z)-7,7-dimethoxy-2-heptene (i) in 52% overall yield. Treatment with dibromocarbene gave 85% of (±)-(2α,3α)-1,1-dibromo-2-methyl-3-(4,4-dimethoxybutyl) cyclopropane. Acid hydrolysis of the dimethylacetal group and reaction with (carbethoxymethylene)triphenylphosphorane produced ethyl (±)-(2E,1′α,3′α)-6-(2,2-dibromo-3- methylcyclopropyl)-2-methylhexenoate in 73% overall yield. Reduction of the ester with DIBAL-H followed by oxidation of the alcohol with PDC in DMF at 0 °C gave 96% of (±)-(2E,1′α,3′α)-6-(2,2-dibromo-3- methylcyclopropyl)-2-methylhexenal (ii). Addition of isopropylidenetriphenylphosphorane to the aldehyde gave 78% of 1a. A similar synthetic sequence starting from 5,5-dimethoxypentanal provided 1b and 7 in 28% and 34% yield, respectively.
12. (b) Schreiber, S. L.; Claves, R. E.; Reagar, S. Org. Synth. Coll. Vol. 7, 168. matrix presented
13. All new compounds were completely characterized by appropriate spectroscopic methods. All gave satisfactory elemental analyses and/or exact mass molecular weights. Tan, L. Ph. D. Dissertation, University of Minnesota, 1995.