Silyl sulfonates silanes

Alternative Routes to Substituted (2-Phenylsulfonylethyl)-trimethylsilanes. Although the fluoride-induced elimination is a reliable and efficient method for synthesizing alkenes, the requisite silyl sulfone precursors are often better prepared by methods which avoid the use of (2). For example, eq 3 illustrates an alternative synthesis of 2,2-dialkyl-2-(phenylsulfonylethyl)trimethyl-silanes involving alkylation of a lithio sulfone with (iodomethyl)-trimethylsilane. ... 

Several examples of Bi(0Tf)34H20-catalyzed Mannich-type reactions of various A-benzyloxycarbonylamino sulfones 1 with silyl enol ethers are summarized in Table 5. A-Benzyloxycarbonylamino sulfones 1 derived from differently substituted benzaldehydes were reacted with trimethyl(l-phenylvinyloxy)silane in dichloromethane at room temperature. The corresponding (3-amino ketones 24 were smoothly obtained (Table 5, entries 1-6). The reaction was efficient using electron-deficient benzaldehyde-derived sulfones, and the corresponding (3-amino ketones 24... 

Four synthetic routes lead to silyl triflates (1) reaction of silyl chlorides with silver triflate (very expensive), (2) reaction of silyl chlorides with triflic acid, (3) reaction of tetraalkylsilanes with triflic acid, and (4) reaction of arylsilanes with triflic (trifluoromethane sulfonic) acid (24-26). The displacement of a chlorine atom and a phenyl group from trimethylsilyl chloride and trimethylphenylsilane indicate that these groups are much more reactive than the alkyl substituents for the synthesis of triflated silanes. We found that the aryl group is over 200 times more reactive than chloride in these reactions (14). We were able to displace two phenyl groups from diphenyl-dimethylsilane in a stepwise manner ... 

Now comes the critical moment. Treatment of 141 with acid (camphor sulfonic acid is used, not because it is enantiomerically pure, but because it is convenient) opens the heterocyclic ring to give the unstable iminium ion that cyclises onto the vinyl silane 142 to give the (5-silyl cation 143 with retention of configuration at the alkene. The product 144 is formed in only moderate yield (52% from 141) but contains no trace of the F-isomer. 

The concept of silyl enol ether synthesis via / -elimination from a Brook rearrangement-derived carbanion also appeared in Wicha s studies on additions of 1-phenyl-l//-tetrazol-5-yl (PT) sulfonyl anions to acyl silanes. When PT sulfone 34 was deprotonated in the presence of acyl(triphenyl)silane, ketone 36 was isolated in good yield after hydrolysis of the silyl enol ether intermediate 35. The mechanism involved addition of the... 

Omega-SLllyl polycarbonates have been hydrosilated with either tertiary silanes or ym-tetramethyldisiloxane to yield silylated polycarbonates or polycarbonate-disiloxane-polycarbonate triblock copolymers.The siloxane-containing polymers exhibit relatively lower Tg and higher thermooxidative stability compared with bisphenol A polycarbonate. Hydrosilation of allyl-terminal poly(alkyleneoxide-co-sulfone) in 1 1 or 2 1 ratio with hydride-terminal polysiloxane leads to ABC and (AB)2C type block-terpolymers, respectively. DSC studies indicate microphase separation, while TGA data point to higher thermal stability for the siloxane... 

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