[762-66-3]  · C6H14Ge  · Allyltrimethylgermane  · (MW 158.78)

(allylation reagent for electrophilic2,3 and nucleophilic reactions4,5)

Physical Data: bp 101 °C.

Solubility: sol ether, hexane, and dichloromethane; insol H2O.

Form Supplied in: not commercially available.

Analysis of Reagent Purity: 1NMR or GC.

Preparative Methods: to a solution of MeMgCl (2.3 M, 395 mL) in diethyl ether was added dropwise allyltrichlorogermane (61 g, 0.277 mol) in nitrogen. The mixture was refluxed for 10 h. After quenching with water, the mixture was extracted with diethyl ether. Careful distillation afforded allyltrimethylgermane (68%).9

Allylgermanes are nucleophilic species which react with electrophiles with allylic inversion.1 Lewis acid-catalyzed Michael addition of the substituted allylgermane (1) to the unsaturated ester (2) takes place at the g-position of (1) with migration of the double bond (eq 1).2 The stereoselectivity of Lewis acid-promoted allylation of chiral dioxane acetals (3) depends on the allylmetal reagent and increases in the order allylsilanes < allylgermanes < allylstannanes, which parallels increased nucleophilicity (eq 2).3 Similar results were obtained by the reaction of the monothioacetal (6) with allylmetal reagents in the presence of Trimethylsilyl Trifluoromethanesulfonate (eq 3). Allylgermane showed ca. 80% syn selectivity irrespective of the stereochemistry of (6), while the reaction of allylstannane was highly dependent on the stereochemistry of the reagent. The reaction of less nucleophilic allylgermane proceeds through an SN1 mechanism involving an oxonium ion, while allylstannane reacts through an SN2-type mechanism.6

Aromatic compounds undergo allylation with allylgermanes by reaction with Iodosylbenzene in the presence of Boron Trifluoride Etherate (eq 4).4 The reaction involves generation of allyliodine(III) species, which can act as an allyl cation equivalent. Allylthallium(III) species, generated from the reaction of allylgermanes with thallium(III) salts, allylate aromatic compounds, alcohols, carboxylic acids, and nitriles.5

The photochemical reaction of allylgermane with 1,4-dicyanonaphthalene gives 1-allyl-4-cyanonaphthalene, which probably involves electron transfer from allylgermane to the electron-deficient 1,4-dicyanonaphthalene (eq 5).7 Thermal ene reaction of allylgermane with Diethyl Azodicarboxylate gives a mixture of stereoisomers of vinylgermanes (eq 6).8

1. Riviere, P.; Riviere-Baudet, M.; Satge, J. In Comprehensive Organometallic Chemistry; Wilkinson, G., Ed.; Pergamon: Oxford, 1982; Vol. 2, Chapter 10.
2. Yamamoto, Y.; Okano, H.; Yamada, J. TL 1991, 32, 4749.
3. Denmark, S. E.; Almstead, N. G. JOC 1991, 56, 6485.
4. Ochiai, M.; Fujita, E.; Arimoto, M.; Yamaguchi, H. CPB 1985, 33, 41.
5. (a) Ochiai, M.; Arimoto, M.; Fujita, E. TL 1981, 22, 4491. (b) Ochiai, M.; Tada, S.; Arimoto, M.; Fujita, E. CPB 1982, 30, 2836. (c) Ochiai, M.; Fujita, E.; Arimoto, M.; Yamaguchi, H. CPB 1983, 31, 86. (d) Ochiai, M.; Fujita, E.; Arimoto, M.; Yamaguchi, H. CPB 1984, 32, 5027.
6. Sato, T.; Otera, J.; Nozaki, H. JOC 1990, 55, 6116.
7. Mizuno, K.; Nishiyama, T.; Terasaka, K.; Yasuda, M.; Shima, K.; Otsuji, Y. T 1992, 48, 9673.
8. Laporterie, A.; Dubac, J.; Lesbre, M. JOM 1975, 101, 187.
9. Petrov, A. D.; Mironov, V. F.; Dolgii, I. E. IZV 1956, 1146.

Masahito Ochiai

University of Tokushima, Japan

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