Introduction
1,1,3,3-Tetramethyldisiloxane (TMDS) is a hydrosiloxane derivative
and has been used in organic synthesis as a mild reducing agent
and intermediate for the preparation of organopolysiloxanes. It
is a rather cheap, little hazardous, safe, volatile liquid boiling
at 71 ˚C and is stable towards air and moisture.
[¹]
It has been used as a
reducing agent for the direct synthesis of alkyl halides from aldehydes
[²]
and for the synthesis
of alkyl halides from epoxides.
[³]
It
was also found to be a mild donor of hydride for selective semihydrogenation
of acetylenes to olefins,
[4]
it is
used for the reduction of aryl chlorides to the corresponding arenes,
[5]
the reduction of unsymmetrical
secondary phosphine oxides to secondary phosphine,
[6]
the reductive cleavage of inert
C-O bonds,
[7]
and the preparation
of aldenamines from carboxamides.
[8]
The
enantioselective reductive Michael cyclization of substrates containing
two α,β-unsaturated carbonyl moieties has been
achieved by the use of a combination of TMDS and chiral copper-bisphosphine
complexes.
[9]
Reduction and reductive
N-alkylation of secondary amides to secondary amines with a ruthenium
complex/TMDS system are readily accomplished.
[¹0]
1,1,3,3-Tetramethyldisiloxane is a by-product of the silicon
industry and the lowest-molecular-weight commercially available
hydrosiloxane derivative now. It can be readily prepared by reduction
of 1,1,3,3-tetramethyl-1,3-dichloro-1,3-disiloxane with a metal
hydride such as lithium aluminum hydride, sodium aluminum hydride,
lithium borohydride, lithium hydride or sodium hydride in tetrahydrofuran.
Scheme 1
