Structural and Chemical Properties of Silyl Radicals

A General Synthetic Approach to the (20S)-Camptothecin Family of Antitumor Agents by a Regiocontrolled Cascade Radical Cyclization of Aryl Isonitriles

“…We therefore investigated silane additives in place of ditin. [33] As shown in Scheme 3, hexamethyldisilane afforded 1 a with a penalty of about 10 % yield relative to the ditin counterpart (compare entries 3 and 1), whereas tetrakis(trimethylsilyl)silane [33b] provided 1 a in 57 % yield (entry 4). This last result, obtained only after most of the other work in this paper was completed, suggests that tetrakis(trimethylsilyl)silane may be a useful substitute for hexamethylditin in the syntheses of (20S)-camptothecin derivatives described below.…”

(Me3Si)3SiH: Twenty Years After Its Discovery as a Radical‐Based Reducing Agent

“…[50,58] These reactions are highly regioselective and give terminal (Me 3 Si) 3 Si-substituted alkenes in good yields. High cis or trans stereoselectivity is also observed, depending on the nature of the substituents at the acetylenic moiety and the experimental conditions.…”

“…For example, when Me 3 Si groups progressively replace methyl groups, the degree of pyramidalization decreases. [50] Bulkier trialkylsilyl substituents, like iPr 3 Si or tBu 2 MeSi groups, considerably increase the persistence of www.chemeurj.org silyl radicals. Indeed, the (tBu 2 MeSi) 3 SiC radical is found to be stable and isolable in the crystal form.…”

Expanding the Repertoire of Molecular Linkages to Silicon: Si–S, Si–Se, and Si–Te Bonds

“…66−68 Assuming the central role of the Si· radical species, the formation of the Si−E bond could occur through two possible pathways. As is well-established in the molecular silane radical literature, 37,56 dialkyl and diaryl disulfides and diselenides can add to the silyl radical through an S H 2 mechanism (Scheme 2a), producing a sulfuranyl or seleranyl intermediate that then collapses to form the Si−ER final product, releasing an equivalent of ·ER (E = S and Se). The equilibria between silanes and thiols under radical conditions have been extensively studied, and although there are few examples of direct coupling of a silane radical, Si·, and a chalcogenide radical, ·ER, to produce Si−ER bonds, there is precedent.…”