Silylation as a protective method in Cadiot-Chodkiewicz couplings

Autor:	R. Eastmond, David R. M. Walton
Rok vydání:	1972
Předmět:	Aqueous solution Silylation Aryl Organic Chemistry Biochemistry Silane Medicinal chemistry chemistry.chemical_compound chemistry Phenylacetylene Yield (chemistry) Reagent Drug Discovery Organic chemistry Oxidative coupling of methane
Zdroj:	Tetrahedron. 28:4591-4599
ISSN:	0040-4020
DOI:	10.1016/0040-4020(72)80040-1
Popis:	Cadiot-Chodkiewicz couplings of arylacetylenes (I), XC6H4CCH (X = H; m-Br, -Me; p-F, -NO2, -OMe) with bromoethynyl(triethyl)silane(II), BrCCSiEt3, yield the silylated diynes, XC6H4(CC)2SiEt3, from which the terminal diynes(III), XC6H4CC)2H, are quantitatively liberated by treatment with aqueous methanolic alkali. Reactions of II with III in turn yield the silylated triynes, XC4H4CC)3SiEt3, which, with alkali, give the free arylhexatriynes, XC6H4(CC)3H(IV). The germanium analogue of II, BrCCGeEt3, likewise couples with I (X = H, p-NO2) to give XC6H4(CC)2GeEt3 or with III to give XC6H4(CC)3GeEt3. The products (X = H) are identical with those obtained from the Grignard reagents, C6H5(CC)nMgBr (n = 2, 3), and bromotriethylgermane. Other XC6H4(CC)nGeEt3 compounds (n = 2,3; excluding X = NO2) were also prepared by the Grignard method. Couplings between phenylacetylene and the reagents, BrCCSiMe3(V), and ICCSiR3 (R = Me, Et) give the appropriate silylated phenylbutadiynes in poor yield because of symmetrical oxidative coupling (iodo compounds) or of base-sensitivity of the trimethylsilyl-acetylene bonds.
Databáze:	OpenAIRE
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