Colin Eaborn

Silicon Reagents for Organic Synthesis : by W.P. Weber. Springer-Verlag, Berlin - Heidelberg - New York, 1983, XVIII + 430 pages, DM 224.

The basic aim of the book is two-fold: to describe routes to functionalized organosilanes and the useful behavior of such silanes, with emphasis placed on the organic moiety; to provide coverage of organosilicon chemistry. Annotation copyright Book News, Inc. Portland, Or.

Synthesis of organotrialkylstannanes. The reaction between organic halides and hexaalkyldistannanes in the presence of palladium complexes

Abstract The aryl halides YC 6 H 4 X (X = Br or I) have been shown to react with the distannanes (R 3 Sn) 2 (R = n-Bu or Me) in toluene in the presence of [Pd(PPh 3 ) 4 ] or [PdBr 2 (PPh 3 ) 2 ] to give the compounds YC 6 H 4 SnR 3 for (a) R = n-Bu, Y = H, p-OMe, o -Me, p -Me, m -Cl, p -Cl, m -CN, p -COCH 3 and m -NO 2 , and (b) R = Me, Y = H, p -OMe, p -Me, p -CN, p -COCH 3 , m -NO 2 and p -NO 2 . Benzyl halides YC 6 H 4 CH 2 X (X = Cl or Br) similarly give YC 6 H 4 CH 2 SnR 3 for (a) R = n-Bu, Y = H, m -OMe, p -OMe, m -Cl, m -CN, and m -NO 2 , and (b) R = Me, Y = m -Cl, m -CN, p -CN and m -NO 2 . These reactions are of special value as preparative procedures in cases in which Grignard or organolithium reagents cannot be used. Allyl chloride and bromide were likewise shown to react with (n-Bu 3 Sn) 2 to give CH 2 CHCH 2 SnBu 3 , but n-BuCl and n-BuBr gave only a trace of n-Bu 4 Sn. The mixed dimetallo species n-Bus 3 SnSiMe 3 was shown to react with aryl bromides YC 6 H 4 Br (X = H, p -OMe, p -Me, or p -Cl) to give the arylsilicon compounds YC 6 H 4 SiMe 3 , with no aryltin products.

Preparation of tris(trimethylsilyl)methyl (“trisyl”) derivatives of silicon

Abstract Treatment of (Me 3 Si) 3 CLi (“trisyl”lithium, TsiLi) with appropriate silicon halides has given a range of compounds of the type (Me 3 Si) 3 CSiRR′X; e.g., TsiSiCl 3 , TsiSiMeCl 2 , TsiSiMe 2 X (X = Cl, OMe), TsiSiPh 2 X (X = F, Cl, OMe), and TsiSiPhMeH. The trisyl group causes very large steric hindrance to nucleophilic displacements at the silicon to which it is attached, so that (unless one or more hydride ligands are present) most of the common displacements at silicon do not occur. However, halides can be reduced to hydrides by LiAlH 4 , and the hydrides can be converted into halides in electrophilic displacements by hallogens. The presence of even one hydride ligand markedly reduces the hindrance, so that, for example, TsiSiPhHI reacts with refluxing methanol to give TsiSiPhH(OMe).

Reactions of organic halides with R3 MMR3 compounds (M = Si, Ge, Sn) in the presence of tetrakis(triarylphosphine)palladium

Abstract Compounds of the type ArSnR 3 (R = Me or Bu), ArGeEt 3 and XC 6 H 4 CH 2 SiMe 3 are formed, though sometimes in poor yield, by interaction of ArHal or XC 6 H 4 CH 2 Hal with the appropriate R 3 MMR 3 compounds in the presence of [Pd(PAr 3 ) 4 ].

Further studies on reactions of organic halides with disilanes catalysed by transition metal complexes

Abstract The interaction of a range of organic halides with (Cl3Si)2 or (Me3Si)2 in the presence of a variety of transition metal catalysts (very predominantly Pd0 or PdII complexes) have been examined. PhSiMe3 was formed from PhCl[m.y., 15%] (m.y. - maximum yield), PhBr (m.y., 92%, with [PdL2Br2] as catalyst (L - PPh3)), and (contrary to earlier reports) PhI (m.y. 51%, with [PdL2I2]). MeSiCl3 was formed from MeBr (m.y., 78% with [PdL4]) and MeI (m.y., 91% with [PdL4]), and EtSiCl3 from EtBr (m.y., 49%, with [PdL2“Br2]; L” - P(C6H4OMe-p)3) and EtI (m.y. 45%, with [PdL4]). Me4Si was satisfactorily formed from MeBr (m.y. 42%, with [PdL4]). Evidence was obtained for the formation of Me3SiCF3 from CF3I. Very poor yields of XC6H4CH2SiMe3 were obtained from XC6H4CH2Br (X - H orp-Me) (with X - H some PhSiMe3 was formed), butp-O2NC6H4CH2SiMe3 was formed in 48% yield fromp-O2NC6H4CH2Cl with [PdL“4] as catalyst. PhCOSiMe3 was formed from PhCOCl (m.y. 52% with [PdL2I2]. The nickel complex [NiL4] was moderately effective as a catalyst for reactions between (Cl3Si)2 and MeBr, EtBr, or PhCH2Br. The new complex [PdL2(SiCl3)2] was prepared by treatment of [PdL4] with (Cl3Si)2 or Cl3SiH, and shown to catalyse the reaction between MeBr and (Cl3Si)2.

Synthesis, structure and reactions of organometallic compounds of Groups 1–3 containing bulky silicon-substituted alkyl groups

Abstract A review is presented of the chemistry of organometallic compounds containing very bulky ligands of the types C(SiMe 2 X) 3 (X = Me, Ph or OMe) and C(SiMe 3 ) 2 (SiMe 2 X) (X = Ph or OMe) attached to metals of Groups 1–3. The structures and reactions of these compounds show novel features not observed for analogues containing less bulky alkyl groups.

Improvements in the preparation and use of [tris(trimethylsilyl)methyl]lithium

Abstract Improvements in the preparation and use of [tris(trimethylsilyl)methyl]lithium are described.

Reaction of tris(trimethylsilyl)methylsilicon halides with methanolic sodium methoxide. Probability of sila-olefin intermediates

Abstract The compounds TsiSiR 2 X [Tsi = Me 3 Si) 3 C; R = Me, X = Cl, Br, I, or R = Ph, X = F, Cl, Br, I)] react with boiling 2 M MeONa-MeOH to give products of the type (Me 3 Si) 2 CHSiR 2 OMe. It is suggested that the reaction proceeds through an elimination, analogous to E 2 eliminations of alkyl halides, involving synchronous attack of MeO − at an Me 3 Si group, liberation of X − , and formation of (Me 3 Si) 2 CSiR 2 . The compounds TsiSiPhMeF TsiSiPhCl 2 react analogously to give (Me 3 Si) 2 CHSiPhMe(OMe) and (Me 3 Si) 2 CHSiPh(OMe) 2 [tha latter presumably by solvolysis of the initially-formed (Me 3 Si) 2 CHSiPhCl(OMe)]. The compounds TsiSiMe 2 OMe and TsiSiMe 3 do not react, while TsiSiMe 2 H gives TsiH. The compound TsiSiCl 3 reacts with 0.1 M MeONa-MeOH to give the substitution and elmination products TsiSiCl 2 (OMe) and (Me 3 Si) 2 CHSi(OMe) 3 in ca. 1 2 ratio.

Di[tris(trimethysilyl)methyl]-zinc and -cadmium☆

Abstract Tris(trimethylsilyl)methyllithium reacts with the anhydrous halides MC1 2 (M = Zn or Cd) to give the compounds [(Me 3 Si) 3 C] 2 M, which show high thermal and chemical stability. They decompose only above 300°C, with formation of (Me 3 Si) 3 CH, and are not attacked by water in refluxing THF. The zinc compound can be steam-distilled without decomposition, and does not react with boiling concentrated hydrochloric acid or with bromine in carbon tetrachloride.

Some unusual methylations and arylations of platinum(II) chlorides by organotin compounds the 13C NMR spectra of bis-aryl(η-cycloocta-1,5-diene)platinum(II) complexes

Abstract Treatment of [Pt(COD)Cl2] with SnMe4 in Cl2CHCHCl2 at 100°C has been shown to give [Pt(COD)(Me)Cl] in 59% yield, while use of Me2SO as solvent gives [PtMe2(Me2SO)2], and hence [PtMe2(PPh3)2] in 50% yield. Interaction of [Pt(COD)Cl2] with Sn(C6H4SMe-p)Me3 gives the polymeric species [Pt(C6H4SMe-p)2]n. Treatment of [Pt(COD)Cl2] with 1-trimethylstannyl- or bis(1,1′-trimethylstannyl)-ferrocene gives [Pt(COD)(C5H4FeC5H5)Cl] or the ferrocenyl-bridged[Pt(COD)Cl(C5H4FeC5H4)Cl(COD)Pt]. Treatment of trans-[Pt2Cl4(PEt3)2] with Sn(C6H4Me-p)Me3 readily brings about replacement of the terminal chloride ligands to give [Pt2(C6H4Me-p)2Cl2(PEt3)2]. The 13C NMR spectra of various [Pt(COD)(C6H4X)2] complexes are reported, and also values of the longest wavelength maximum, λmax, in the visible spectrum of [Pt(C6H4X)2(BIPY)]. The values of the 13C chemical shifts for the olefinic protons of the COD complexes given an excellent linear correlation with σ° values of the X groups, and with the values of λmax for the BIPY complexes.