1-Methoxy-3-methyl-1-trimethylsilyloxy-1,3-butadiene

[73311-51-0]  · C9H18O2Si  · 1-Methoxy-3-methyl-1-trimethylsilyloxy-1,3-butadiene  · (MW 186.36) (E)

[76927-59-8] (Z)

[76915-33-8]

(diene in Diels-Alder reactions; nucleophile; alkene substrate)

Physical Data: bp 40 °C/0.3 mmHg.

Analysis of Reagent Purity: for the thermodynamically favored isomer of the diene: 1H NMR (C6D6, 270 MHz) d 4.90 (br, d, J = 2.7 Hz, 1 H), 4.65 (m, J = 1.4, 2.7 Hz, 1 H), 4.23 (s, 1 H), 3.15 (s, 3 H), 2.00 (dd, J = 0.7, 1.4 Hz, 3 H), 0.14 (s, 9 H); 13C NMR (15 MHz, C6D6, off-resonance decoupled) d 159.4 (s), 141.9 (s), 110.2 (t), 83.7 (d), 56.5 (q), 25.6 (q), 2.2 (q); IR (hexane) 1660 cm-1. The only difference between the 1H NMR (C6D6) spectra of the two diene isomers are the CH3O resonances, which appear at d 3.15 and 3.12.

Preparative Method: silyl enolization of methyl 3-methyl-2-butenoate gives a 1:1 mixture of (Z) and (E) isomers.1

Purification: distillation at 65 °C/1 mm Hg or heating the mixture to 115 °C for 40 min causes isomerization to the thermodynamically favored isomer.

Handling, Storage, and Precautions: silyl migration occurs at 117 °C.1a,2 Use in a fume hood.

Diels-Alder Reactions.

This diene has been used extensively in carbo-Diels-Alder reactions with a wide variety of quinones,3 a trisubstituted alkene,4 a b-phenylsulfinylnitroalkene,5 and a tetrachlorocyclopropane (to prepare a troponoid).6 Dienophiles that have been used with the diene in hetero-Diels-Alder reactions include an orthoquinone (eq 1),3g thioaldehydes (eq 2),7 and imine-TiCl4 complexes.8

Alkylations.

With one exception,9 the 3-methyl substituent of this diene appears to encourage predominantly g- over a-attack in reactions with electrophiles such as 1,3-dithienium tetrafluoroborate (eq 3),10 PCl3 or AsCl3,11 the PhSCl adduct of dihydropyran,12 and PhSCl (eq 4).1d The use of i-Pr or t-Bu ester analogs of this diene and/or bulky electrophiles further enhances g selectivity.13

Chrysanthemic acid derivatives undergo Titanium(IV) Chloride-catalyzed reactions with the diene (eq 5).14 Homo coupling of the diene to give unsaturated esters has also been reported under TiCl4-catalyzed conditions (eq 6).15

Amination.

Addition of 3-acetoxyaminoquinazolinone to the diene occurs at both double bonds to give a mixture of intermediate aziridines which then ring open (eq 7).16


1. (a) Casey, C. P.; Jones, C. R.; Tukada, H. JOC 1981, 46, 2089. (b) Fleming, I.; Goldhill, J.; Paterson, I. TL 1979, 3205. (c) Savard, J.; Brassard, P. T 1984, 40, 3455. (d) Savard, J.; Brassard, P. TL 1979, 4911.
2. Anderson, G.; Cameron, D. W.; Feutrill, G. I.; Read, R. W. TL 1981, 22, 4347.
3. (a) Kelly, T. R.; Ma, Z.; Xu, W. TL 1992, 33, 7713. (b) Kim, K. J.; Lee, C. J.; Yang, I. K. J. Sci. Res. Inst. Han. Nam. Univ. 1986, 16, 153 (CA 1987, 107, 115 342h). (c) Cameron, D. W.; Feutrill, G. I.; Gibson, C. L.; Read, R. W. TL 1985, 26, 3887. (d) Benfaremo, N.; Cava, M. P. JOC 1985, 50, 139. (e) Iwao, M.; Kuraishi, T. BCJ 1987, 60, 4051. (f) Roberge, G.; Brassard, P. JOC 1981, 46, 4161. (g) Paquet, J.; Brassard, P. CJC 1989, 67, 1354.
4. Cameron, D. W.; Read, R. W.; Stavrakis, J. AJC 1987, 40, 1831.
5. Jung, M. E.; Grove, D. D. CC 1987, 10, 753.
6. Banwell, M. G.; Knight, J. H. CC 1987, 14, 1082.
7. (a) Vedejs, E.; Eberlein, T. H.; Mazur, D. J.; McClure, C. K.; Perry, D. A.; Ruggeri, R.; Schwartz, E.; Stults, J. S.; Varie, D. L.; Wilde, R. G.; Wittenberger, S. JOC 1986, 51, 1556. (b) Vedejs, E.; Stults, J. S. JOC 1988, 53, 2226.
8. Brandstadter, S. M.; Ojima, I. TL 1987, 28, 613.
9. Loreto, M. A.; Pellacani, L.; Tardella, P. A. TL 1989, 30, 5025.
10. Paterson, I.; Price, L. G. TL 1981, 22, 2833.
11. Pellon, P.; Himdi-Kabbab, S.; Rault, I.; Tonnard, F.; Hamelin, J. TL 1990, 31, 1147.
12. Alexander, R. P.; Paterson, I. TL 1983, 24, 5911.
13. Fleming, I.; Goldhill, J.; Paterson, I. TL 1979, 3209.
14. Ohno, M.; Matsuoka, S.; Eguchi, S. JOC 1986, 51, 4553.
15. Hirai, K.; Ojima, I. TL 1983, 24, 785.
16. Atkinson, R. S.; Kelly, B. J.; Williams, J. T 1992, 48, 7713.

Megan Murphy

Zeneca Pharmaceuticals, Wilmington, DE, USA



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