Synthesis of bulky tris[(dimethyl(alkyl/aryl)silyl)methyl]stannanes as radical based reducing agents

The synthesis of novel bulky tris[dimethyl(ethyl/benzyl/p-tolyl/α-naphthyl)silylmethyl]stannanes (1–4) is described. Alkylation of SnCl4 with Me2(ethyl/p-tolyl)SiCH2MgBr (10–11) gave mainly the triorganotin chlorides [(Me2(ethyl/p-tolyl)SiCH2)]3SnCl 14 and 15, which were isolated by silica gel chromatography. Reduction of 14 and 15 with LiAlH4 in THF gave the corresponding triorganotin hydrides 1 and 2, respectively. [Me2(benzyl/α-naphthyl)SiCH2]3SnCl 16 and 17, generated by the alkylation of SnCl4 with Me2(benzyl/α-naphthyl)SiCH2MgBr 12 and 13, were inseparable from the minor product [Me2(benzyl/α-naphthyl)SiCH2]2SnCl218 and 19, respectively. Treatment of the mixtures of 16/18 and 17/19 with NaOH furnished the corresponding mixtures of stannoxanes, from which the hexakisdistannoxanes [Me2(benzyl/α-naphthyl)SiCH2]6Sn2O 20 and 22 were isolated from the minor dialkyltin oxide derivatives [Me2(benzyl/α-naphthyl)SiCH2]2SnO in good yields. Reduction of 20 and 22 with BH3 in THF gave [Me2(benzyl/α-naphthyl)SiCH2]3SnH (3 and 4), respectively in good yields. 1H, 13C, 119Sn, 29Si NMR characteristics of the newly synthesized compounds are included.

Alkylation of SnCl4 with Grignard reagents Me2(R)SiCH2MgBr (R = Et, Bn, p-tolyl, α-naphthyl) gave mainly [(RMe2SiCH2)]3SnCl as mixtures with [(RMe2SiCH2)]2SnCl2. The [Me2(ethyl/p-tolyl)SiCH2)]3SnCl were purified by silica gel chromatography and then subjected to LiAlH4 reduction to give the corresponding tin hydrides [(Me2(ethyl/p-tolyl)SiCH2]3SnH. The inseparable mixtures of [Me2(benzyl/α-naphthyl)SiCH2]3SnCl and [RMe2(benzyl/α-naphthyl)SiCH2]2SnCl2 were converted into the corresponding stannoxanes [Me2(benzyl/α-naphthyl)SiCH2)]6Sn2O and [Me2(benzyl/α-naphthyl)SiCH2]2SnO, from which the former stannoxanes were isolated and reduced to the corresponding tin hydrides [Me2(benzyl/α-naphthyl)SiCH2]3SnH.Figure optionsDownload as PowerPoint slideHighlights
► Synthesis of bulky tris[(dimethyl(Ethyl, Benzyl, p-tolyl, α-naphthyl)silyl)methyl]stannanes.
► Alkylation of SnCl4 with Me2(R)SiCH2MgBr (R = Et, Bn, p-tolyl, α-naphthyl).
► Separation of tin monochlorides [(RMe2SiCH2)]3SnCl and tin dichlorides derivatives [(RMe2SiCH2)]2SnCl2.
► Reduction of [(RMe2SiCH2)]3SnCl and hexakisdistannoxanes [(Me2RSiCH2)]6Sn2O.