Preparation and Structure of Alkenyl- and Alkynyl-Substituted Polysilamod­ules HC(SiMe₂SiMe₂)₃CR

Abstract

Facile methods for the introduction of alkenyl and alkynyl groups at the bridgehead position of polysilamodule HC(SiMe₂SiMe₂)₃CH are established. Deprotonation of the module with BuLi/t-BuOK in THF at -40 °C followed by alkylation with bromoacetaldehyde diethyl acetal gives the corresponding acetal, which was hydrolyzed with zinc chloride, yielding a formylmethyl-substituted cage compound. Treatment of the aldehyde with triflic anhydride in the presence of 2,6-di-t-butyl-3-methylpyridine produced the corresponding enol triflate consisting of a 4:1 mixture of E and Z isomers. Palladium-catalyzed cross-coupling of the triflate with organometallic reagents afforded alkenyl group-substituted cage molecules in good yields. Meanwhile, lithiation of phenylthio-substituted cage derivative with lithium 4,4′-di-tert-butylbiphenylide in THF followed by transmetalation with copper iodide and subsequent coupling with iodoalkynes allowed us to prepare alkynyl-substituted polysilacage compounds. The structures were determined by X-ray diffraction of single crystals.

Key words

silicon - cage compounds - bicyclo[2.2.2]octane - alkenyl - alkynyl

References

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5

Crystallographic data of (E)-9 have been deposited at the Cambridge Crystallographic Data Centre with the deposition number CCDC 236989.

7

Nickel-catalyzed reaction of phenylmagnesium bromide with 9 turned out futile: the reason is not clear.

8

Crystallographic data of 10 have been deposited at the Cambridge Crystallographic Data Centre with the deposition number CCDC 236990: colorless plates: C₂₂H₄₄Si₆, M = 477.10, monoclinic, space group P2 (1)/c, a = 16.0900(9), b = 9.4196 (5), c = 19.8143 (11) Å, β = 106.4620 (10)°, V = 2880.0(3) ų, Z = 5, D_calc = 1.375 g/cm³, F(000) = 1300, T = 293 K, λ(Mo-K_α) = 0.71073 Å, 2θ_max = 54.0°, R1 = 0.0481, wR2 = 0.1208, Goodness of fit = 0.895; Number of data = 22549, Number of unique data = 8057 (R _int = 0.0281).

11

Crystallographic data of 17 have been deposited at the Cambridge Crystallographic Data Centre with the deposition number CCDC 236991: colorless prisms: C₂₂H₄₂Si₆, M = 475.08, monoclinic, space group P2 (1)/c, a = 15.3584 (10), b = 9.6527 (6), c = 20.1968 (13) Å, β = 110.8280 (10)°, V = 2798.5 (3) ų, Z = 5, D_calc = 1.128 g/cm³, F(000) = 1032, T = 293 K, λ(Mo-K_α) = 0.71073 Å, 2θ_max = 54.0°, R1 = 0.032, wR2 = 0.087, Goodness of fit = 1.036; Number of data = 21622, Number of unique data = 7860 (R _int = 0.0192).