Reducing agents Et3SiH

Reductive Amidation of Aldehydes. The reductive amidation of aldehydes using an organosilane as the reducing agent has been realized. Benzaldehyde reacts over a 74-hour period with triethylsilane and acetonitrile in 75% aqueous sulfuric acid at room temperature to produce an 80% isolated yield of N-benzylacetamide (Eq. 169).313 Octanal fails to react under the same conditions.313 Reductive amidation of aldehydes also occurs with the reagent combination Et3SiH/TFA/primary amide (Eq. 170).326... 

If one of the reactions in a radical chain sequence is too slow to compete effectively with radical-radical reactions, the chain will collapse. Slow reactions of simple silanes such as Et3SiH with alkyl radicals precludes their use in the tin hydride method. Although quite reactive with alkyl radicals, thiols and selenols fail in the tin hydride method because the thiyl and selenyl radicals do not react rapidly with organic halide precursors. Nonetheless, it is possible to use thiols and selenols in tin hydride sequences when a Group 14 hydride is used as a sacrificial reducing agent. The thiyl or selenyl radical reacts with the silane or stannane rapidly, and the silicon- or tin-centered radical thus formed reacts rapidly with the organic halide [8], In practice, benzeneselenol in catalytic amounts has been used in radical clock studies where BusSnH served as the sacrificial reductant [9]. 

X = H when reducing agent is 136. X = Et3Si when reducing agent is Et3SiH Scheme 8.23... 

Replacement of the iodine or bromine substituent of a perfluoroalkyl iodide or bromide with hydrogen is a process which is a side reaction in most of the reduc-tively-catalyzed perfluoroalkylation processes described earlier. If one wishes to carry out such a reaction synthetically, it may be accomplished easily by use of any of a number of hydrogen atom transfer agents such as n-Bu3SnH, -Bu3GeH, (TMS)3SiH, or Et3SiH. 

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