Phenylsilane PhSiH

Diiodosilane l2SiH2 1872, prepared by treatment of phenylsilane PhSiHs with iodine, via PhSiH2l, in the presence of catalytic amounts of ethyl acetate at -20 °C, is much more electrophilic than Me3SiI 17 and therefore converts secondary alcohols such as 2-octanol 1871, at room temperature with Walden inversion, into iodides such as 1873 in 93% yield whereas the diol 1874 is nearly quantitatively converted into the monoiodobutane 1875 and only traces of the diiodobutane 1876 [88, 89] (Scheme 12.26). 

An additional approach toward the preparation of tertiary phosphines is by the reduction of more highly coordinated phosphorus species, particularly phosphine oxides [0=PR3] and phosphine sulfides [S=PR3] (see Section 5.2), but also phosphonium salts [ILtP+X"] and quasiphosphonium salts [R3P-YR +X ] (see Sections 4.2 and 4.4). Numerous reducing agents have been used to accomplish these conversions, including hexachlorodisilane [CbSi-SiCft], trichlorosilane [HSiCft], phenylsilane [PhSiHs], and lithium aluminum hydride [LiAlH4]. 

For the deprotection of the allyl group (Glu(OAll)), prepare a solution containing phenylsilane (PhSiHs) (14 equiv. with respect to the loaded amino acid), Tetrakis(triphenylphosphine) palladium(O) (Pd(PPh3)4) (0.05 equiv. with respect to the loaded amino acid—see Note 16) in THF (30 mL for 1 mmol of loaded amino acid). 

Hydrosiiation of dienes using 1 mol% [Nd(Cp 2) CH(SiMe3)2 ] has been described by Tanaka et al. With PhSiHs, isoprene yields ( )-2-methyl-2-butenyl-phenylsilane as the major product, whereas 1,5-hexadiene and 1,6-heptadiene yield a cyclopentylmethylsilane as the primary product. 

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