Physical properties
bp 111 °C; bp 54–56 °C/90 mmHg
Uses
It is widely used as propargylic anion equivalents; three-carbon synthons for
[3 + 2] annulations leading to five-membered compounds including
cyclopentenes,4 dihydrofurans, pyrrolines, isoxazoles,
furans, and azulenes.
Uses
3-(Trimethylsilyl)-1,2-butadiene may be used for the synthesis of γ-(trimethylsilyl)allylborane.
Preparation
1-methyl-1-(trialkylsilyl)allenes can be
conveniently prepared by the method of Vermeer. Silylsubstituted
propargyl mesylates thus undergo SN2 displacement
by the organocopper reagent generated from methylmagnesium
chloride, copper(I) bromide, and lithium bromide
1-Methyl-1-(trimethylsilyl)allene is produced in 52% yield
from commercially available (trimethylsilyl)propargyl alcohol
in this fashion (eq 1). The t-butyldimethylsilyl and triisopropylsilyl
analogs are synthesized by the same method in 90%
and 58% yield, respectively. Propargyl alcohols bearing these
and other trialkylsilyl groups can be prepared by treatment
of propargyl alcohol with n-butyllithium and the appropriate
trialkylsilyl chloride. Allenylsilanes bearing other C-1 substituents
can be prepared in an analogous manner by using the
appropriate Grignard reagents.
