Stereoselective preparation of (Z)-2-(trialkylsilyloxy)-2-alkenals by retrocycloaddition reactions of 4H-4-alkyl-5-(trialkylsilyloxy)-1,3-dioxins. Useful reactants for Lewis acid catalyzed [4 + 3] cyclizations

Organic Letters

Volumn 3, Issue 22, 2001, Pages 3553-3555

  Aungst Jr , Ronald A ^a   Funk, Raymond L ^a  

^a PENNSYLVANIA STATE UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ALKENE; DIOXIN; SILOXANE;

ARTICLE; CATALYSIS; CHEMISTRY; CYCLIZATION; STEREOISOMERISM;

ALKENES; CATALYSIS; CYCLIZATION; DIOXINS; SILOXANES; STEREOISOMERISM;

EID: 0035511672     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol016668f     Document Type: Article

References (19)

1. (a) Noyori, R.; Hayakawa, Y. Org. React. 1983, 29, 163.
2. (b) Hoffmann, H. M. R. Angew. Chem., Int. Ed. Engl. 1984, 23, 1.
3. (b) Mann, J. Tetrahedron 1986, 42, 4611.
4. (c) Hosomi, A.; Tominaga, Y. Comprehensive Organic Synthesis; Trost, B. M. Fleming, I., Eds.; Pergamon: Oxford, 1991; Vol. 5, pp 593-615.
5. (d) Rigby, J. Org. React. 1997, 51, 351.
6. (e) Harmata, M. Tetrahedron 1997, 53, 6235.
7. Sasaki, T.; Ishibashi, Y.; Ohno, M. Tetrahedron Lett. 1982, 23, 1693.
8. 4, -78 °C, 6 h), see: Blackburn, C.; Childs, R. F.; Kennedy, R. A. Can. J. Chem. 1983, 61, 1981.
9. For the preparation and cycloaddition reactions of (E)-2-alkenals, see: (a) Funk, R. L.; Bolton, G. L. J. Am. Chem. Soc. 1988, 110, 1290.
10. 2-(Acyloxy)acroleins, see: (b) Funk, R. L.; Yost, K. J., III. J. Org. Chem. 1996, 61, 2598.
11. 2-Acylaeroleins, see: (c) Funk, R. L.; Feamley, S. P.; Gregg, R. Tetrahedron 2000, 56, 10275.
12. 2-(Amido)acroleins, see: (d) Maeng, J.-H.; Funk, R. L. Org. Lett. 2001, 3, 1125.
13. (e) Greshock, T. J.; Funk, R. L. Org. Lett. 2001, 3, 3511.
14. (f) (Z)-2-Acyl-2-enals, see: Aungst, R. A., Jr.; Funk, R. L. J. Am. Chem. Soc. 2001, 123, 9455.
15. Harmata, M.; Sharma, U. Org. Lett. 2000, 2, 2703.
16. We have been unable to efficiently alkylate the enolate derivative of 1,3-dioxin-5-one due to a competing aldol reaction. For similar problems, see: Majewski, M.; Cleave, D. M.; Nowak, P. Can. J. Chem. 1995, 73, 1616.
17. Stereochemical assignments for all adducts were made using NOESY experiments. See the Supporting Information for the diagnostic observations. The regiochemistry for entries 7 and 9 was determined by 2D COSY NMR experiments. The methine proton on the silyloxy carbon of the major product of entry 7 was directly coupled to two allylic protons which were both coupled to one another as well as the vinylic proton. The methine proton on the silyloxy carbon of the major product of entry 9 was coupled to only one other proton which in turn was coupled to the methyl protons as well as one of the vinylic protons.
18. A crossover experiment suggests that the silyl group is transferred both intra- and intermolecularly. Thus, when the cyclization shown in entry 2 was performed in the presence of an equivalent amount of enal 12, the endo adduct shown in entry 2 was obtained accompanied by the endo adduct of entry 1 (86:14, respectively). Similarly, the endo cyclization product derived from enal 12 (TBS ether) was accompanied by the corresponding endo TES ether adduct (86:14, respectively).
19. This protocol was necessary since thermolysis of the dioxin of entry 9 in refluxing toluene gave rise to the product derived from an intramolecular Diels - Alder reaction of the intermediate 2-(tert-butyldimethylsilyloxy)-2-enal.