DI-TERT-BUTYLDICHLOROSILANE

mp ?15°C; bp 190°C/729 mmHg; d 1.009 g cm?3.

The presence of the bulky t-butyl groups in di-t-butyldichlorosilane has been found to increase the Si–C bond lengths slightly and to widen the CSiC bond angles by 11.1? relative to dichlorodimethylsilane as determined by electron diffraction and molecular mechanics calculations.
The di-t-butylsilylene protecting group for diols was introduced by Trost and Caldwell and used in a total synthesis of deoxypillaromycinone.It is introduced by the reaction of di-tbutyldichlorosilane with a 1,2- or 1,3-diol in acetonitrile in the presence of triethylamine and 1-hydroxybenzotriazole (HOBt) at 45–90°C (eq 1). For a related, highly reactive reagent see di-t-butylsilyl Bis(trifluoromethanesulfonate).

can be conveniently prepared by chlorination of di-t-butylsilane (CCl4/PdCl2 (cat), 85%)but various other methods of preparation have been reported.

Purify it by fractional distillation. 20 1.01. It is a colourless liquid with a pleasant odour and does not fume in moist air, but does not titrate quantitatively with excess of dilute alkali. [Tyler et al. J Am Chem Soc 70 2877 1948.] Di -tert-butyl silyl bis(trifluoromethanesulfonate) [85272 -31 -7] M 440.5, b 73.5 -7 4 . 5o/0.35mm, d 4 Purify it by fractional distillation at high vacuum. 20 1.36 (see pK for triflic acid). It is a pale yellow liquid which should be stored under argon. It is less reactive than the diisopropyl analogue. The presence of the intermediate monochloro compound can be detected by 1H NMR, (CHCl3): tert-Bu2Si(OTf)2 [ 1.25s], but impurities have 1.12s for tert-Bu2Si(H)OTf and 1.19s for tert-Bu2HSi(Cl)OTf. [Deslongchamps Tetrahedron Lett 23 4871 1982, Deslongchamps Aldrichimica Acta 17 72 1984.] TOXIC.