Transformation of a Dialkyldisilyne via Single-electron Oxidation and Cycloaddition

概要

Disilynes (silicon–silicon triply bonded compounds) are silicon analogs of alkynes and the
properties of disilynes are different from those of alkynes. In general, disilynes have a narrow
HOMO-LUMO gap and high reactivity compared to alkynes, which is derived from weak siliconsilicon π bonds. Recent research progress enables that disilynes are synthesized as stable
compounds by taking advantage of kinetic stabilization with bulky substituents on the unsaturated
silicon atoms. Since the independent reports on the synthesis of stable of disilynes by Sekiguchi
and Wiberg groups in 2004, the chemistry of disilynes have been drastically developed. Recently,
our group have succeeded in the synthesis of dialkyldisilyne 1 which is kinetically stabilized by
the bulky alkyl substituent, 1,1-bis(trimethylsilyl)-3,3-dimethylbutyl group (abbreviated as Rs
group, Chart 1). 1 is a useful unit for construction of cyclic silicon compounds; we have reported
synthesis of group-10 transition metal-disilyne complexes and benzodisilacyclobutadienes from
1. However, the knowledge of the reactivity of disilynes remains limited compared to that of
alkyne, a common functional group in organic chemistry.
As dialkyldisilyne 1 has a high-lying HOMO, the author anticipated that oxidation reaction
of 1 would proceed easily. In chapter 2, the author describes a catalytic isomerization of 1 to
tetrasilabicyclo[1.1.1]pentane derivative 2 upon single-electron oxidation.
In chapter 3, the author describes the synthesis and isolation of silacyclopropenylsilylene
as an N-heterocyclic carbene (NHC) complex (3·IMe4).
Chart 1. ...