Silanes synthesis

Use of chromic acid-based oxidation reagents often results in silicon-carbon bond cleavage (Scheme 13)5, although such an oxidation has been used to produce a-cyclopropyl acyl silanes (vide infra, Section III.E)85. In an interesting development, this handicap of ready silicon-carbon bond cleavage during oxidation of a-hydroxy silanes has been cleverly utilized in an acyl silane synthesis by incorporation of two silicon moieties in the substrate (Scheme 14). 

A much more general method for acyl silane synthesis involving silyl diazo intermediates is illustrated in Scheme 1688. The lithiated derivative of trimethylsilyl diazomethane reacts smoothly with alkyl halides in THF solution to give a-trimethylsilyl diazoalkanes in good yields. Oxidative cleavage of the diazo moiety is effected using 3-chloroperbenzoic acid in benzene solution, to give access to a wide variety of acyl silanes in yields of up to 71%. A phosphate buffer (pH 7.6) is used to prevent side reactions. Aromatic acyl silanes clearly cannot be prepared by this chemistry since an aromatic nucleophilic substitution reaction would be required. 

One general method for acyl silane synthesis particularly successful for a-cyclopropyl examples (and even an a-cyclobutyl example) involves treatment of acid chlorides with lithium tetrakis(trimethylsilyl) aluminum or lithium methyl tris(trimethylsilyl) aluminium and cuprous cyanide (vide supra, Section III.A.3)77. For example, cyclopropyl acyl silane (23) was obtained in 89% yield by this process. Improved procedures use lithium t-butyldimethylsilyl cuprate78 and a dimethylphenylsilyl zinc cuprate species79,80 as reagents. 

Reagents A Convenient Route to sec- and tert- 6-Alkylpurines. Tetrahedron Lett. 1996, 37, 1285-1288. (c) Dvorakova, H. Dvorak, D. Holy, A. Synthesis of Acyclic Nucleotide Analogues Derived from 6-(sec- or tert-Alkyl) purines via Coupling of 6-Chloropurine Derivatives with Organocuprates. Collect. Czech. Chem. Commun. 1998, 63, 2065-2074. (d) Hocek, M. Holy, A. Perfluoroalkylation of 6-Iodopurines by Trimethyl(perfluoro-alkyl)silanes. Synthesis of 6-(Perfluoroalkyl)purine Bases, Nucleosides and Acyclic Nucleotide Analogues. Collect. Czech. Chem. Commun. 1999, 64, 229-241. 

Tris- and Tetrakis-[oligo(phenylenevinylene)]-silanes Synthesis and Luminescence Behavior... 

Heteroaromatic-Substituted Silanes — Synthesis, Lithium Derivatives and Anionic Rearrangements... 

Koe J (2008) Contemporary poly silane synthesis and functionalisation. Polym Int 58(3) 255-260... 

D. Habich and F. Effenberger, Preparation of Aryl- and Heteroaryltrimethyl-silanes . Synthesis, 1979, 841. 

Kuninobu, Y, Ishii, E., Takai, K. 2007. Rhenium- and gold-catalyzed coupling of aromatic aldehydes with tiimethyl(phenylethynyl)silane Synthesis of diethynylmethanes. Angew. Chem. Int. Ed. 46 3296-3299. 

Quan, Z. Zuju, M. Lizhong, N. Jianding, C. 2007. Novel phenyl acetylene terminated poly(carborane-silane) Synthesis, characterization, and thermal property. J. Appl. Polym. ScL, 104 2498-2503. 

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