Computational study of reaction pathways in the course of interaction of deactivated silylenes with buta-1,3-diene

Computational study of 2-vinylsilirane to silacyclopent-3-ene rearrangement

“…It should be noted that transition states of the same types as TS2 and TS3 have been found on the B3LYP/6-31G(d) PESs of several other 1,3-butadiene-silylene systems [27]. The existence of two different suprafacial channels (si and sr) for the degenerate [1,3]sigmatropic rearrangement of allylsilane (and its heavier analogs) were previously reported by Takahashi and Kira [28].…”

The Perchlorinated Silanes Si2Cl6 and Si3Cl8 as Sources of SiCl2

“…The base does not, however, aid the extrusion of SiCl 2 by complex formation with the reactant 1. [14] We studied several pathways for the DMB addition reaction of the free SiCl 2 ( Figure 5) [15] and of the base-stabilized SiCl 2 ·NMe 3 (Figure 6). Both pathways (stepwise and concerted) identified for the free SiCl 2 commence with a (slightly endoergic) trans!cis isomerization of DMB, followed by the formation of a weak encounter complex SiCl 2 ·DMB, in which the silylene coordinates to one of the double bonds in cis-DMB.…”

Reaction of an Overcrowded 1,2-Diaryl-1,2-dibromodisilene with 1-Vinylcyclohepta-1,3,5-triene: Isolation of a 2-Vinylsilacyclopropane Derivative and Its Thermal Conversion to a Silacyclopent-3-ene Derivative

“…Since this reaction showed no intermediate, it is still unclear experimentally whether bromosilylene 2 undergoes addition with buta-1,3-dienes by direct [1+4]-cycloaddition or stepwise formation of 3 via the [1+2]-cycloaddition as proposed by theoretical calculations. 5 During the course of our studies on the construction of silicon-containing azulene skeleton, we found the reaction of disilene 1 with 1-vinylcyclohepta-1,3,5-triene 4 having four conjugated double bonds, resulting in the site-selective formation of 2-vinylsilacyclopropane derivative 5 and the following stereo-selective isomerization to silacyclopent-3-ene derivative 6 (Scheme 4). The reaction of dibromodisilene 1 with an excess amount of 1-vinylcyclohepta-1,3,5-triene 4 in hexane at ambient temperature resulted in quantitative, regioselective, and stereoselective formation of compound 5 (Scheme 4).…”

“…4 On the other hand, Boganov et al proposed that the reactions of halogen-substituted silylenes proceed via path (c) the 1,3-sigmatropic rearrangement of 2-vinylsilacyclopropane. 5 Thus, 2vinylsilacyclopropanes should be important intermediates. In general, however, these reactions proceed promptly to give thermodynamically favored silacyclopent-3-enes, and the successful observation of the conversion from detectable 2-vinylsilacyclopropane to silacyclopent-3-ene had been limited to our previous report using bulky silylene A, Tbt(Mes)Si: (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl) (Scheme 2).…”