Lithium, [3-[tris(1-methylethyl)silyl]-2-propynyl]-

Physical properties

(precursor) bp 100–101 °C/5 mmHg; d 0.813 g cm?3.

The Uses of Lithium, [3-[tris(1-methylethyl)silyl]-2-propynyl]-

3-Lithio-1-triisopropylsilyl-1-propyne can be used as functionalized nucleophilic C3 building block; forms C–C bonds with many carbon electrophiles.
The title reagent was conceived as an improved version of TMS–C≡C–CH2Li. The bulky triisopropylsilyl (TIPS) group provides efficient screening of the carbon atom to which it is attached, and it therefore usually forms propargylic rather than allenic products. The TIPS group is much more inert in basic and nucleophilic reaction mixtures than the widely used TMS group. At the same time, TIPS (in contrast to tri-t-butylsilyl) is commercially available, easily introduced, and readily cleaved (F?) from the product. It is made by deprotonation of 1-TIPS-propyne using n-butyllithium in ether, better without than with TMEDA added,5 or t-butyllithium in ether/pentane, or preferably n-BuLi in THF (?20 °C, 15 min). 1-TIPS-propyne can be prepared from propyne by silylation of either its lithio derivative using TIPS triflate or of the bromomagnesium derivative using TIPS chloride; it is also commercially available.