L. I. Belousova

Acyl Iodides in Organic Synthesis: IX. Cleavage of the Si-O-C and Si-O-Si Moieties

Reactions of acyl iodides RCOI (R = Me, Ph) with organosilicon compounds involve cleavage of the Si-O-C and Si-O-Si fragments. Acetyl iodide reacts with alkyl(alkoxy)silanes with evolution of heat, and cleavage of the Si-O bond results in the formation of oligo-or polysiloxanes, alkyl iodides, and alkyl acetates. 1,3-Diacetoxytetramethyldisiloxane is formed in the reaction of acetyl iodide with dimethoxy(dimethyl)silane. Acyl iodides readily react with 1-ethoxysilatrane to give 1-acyloxysilatranes as a result of cleavage of the C-O bond. The reaction of acetyl iodide with hexaethyldisiloxane yields triethylsilyl acetate and triethyliodosilane, while in the reaction with octamethyltrisiloxane iodo(trimethyl)silane and dimethyl(trimethylsiloxy)silyl acetate are obtained.

Acyl iodides in organic synthesis. Reactions of acetyl iodide with urea, thiourea, and their N,N′-disubstituted derivatives

Acetyl iodide reacted with urea and its derivatives to give the corresponding N-substituted products. The reactions of acetyl iodide with thiourea, N,N′-dimethylthiourea, imidazolidine-2-thione, and hexahydropyrimidine-2-thione resulted in the formation of S- or N-acetyl derivatives, depending on the temperature and structure of the sulfur functionality (thione or thiol). By contrast, in the reaction of acetyl iodide with N,N′-bis(3-triethoxysilylpropyl)thiourea one ethoxy group on the silicon atom was replaced by iodine with formation of N-{3-[(diethoxy)iodosilyl]propyl}-N′-[3-(triethoxysilyl)propyl]thiourea. The latter decomposed on heating to give 3-triethoxysilylpropyl isothiocyanate and silicon-containing polymer with the composition C45H97IN6O14.5S3Si6.

Silyl- and germylmercurials in organic synthesis. A new route to O-silylated and O-germylated enolates

Abstract The exchange reaction of α-mercurated ketones with bis(triethylsilyl)- (I) and bis(triethylgermyl)mercury (II) leads to the formation of the corresponding triethylsilyl and triethylgermyl enol ethers. O -Silylated and O -germylated enolates derived from ketones and aldehydes can be also prepared by treating mercurials I and II with appropriate α-bromo-carbonyl compounds. This new pathway also represents the best available method for preparing bromo-containing triethylsilyl and triethylgermyl enol ethers. NMR and IR spectral characteristic useful in the identification and characterization of these and related compounds are summarized.

Reaction of carboxylic acids with tetrachlorosilane

Tetrachlorosilane reacted with carboxylic acids RCOOH (R = Me, Bu, t-Bu) to give the corresponding acid chlorides RCOCl in 75–95% yield. The reactions of SiCl4 with trichloroacetic and 2-fluorobenzoic acids (R = Cl3C, 2-FC6H4) occurred more difficultly, presumably for steric reasons, and the yields of the corresponding acid chlorides were 11 and 22%, respectively. Tetrachlorosilane failed to react with stearic acid under analogous conditions. Products of the reactions of SiCl4 with chloroacetic and benzoic acids RCOOH (R = ClCH2, Ph) were tetraacyloxysilanes Si(OCOR)4, and tetrakis(chloroacetoxy)silane was formed in almost quantitative yield. The reaction of SiCl4 with glutaric acid led to the formation of a rubber-like polymeric material with the composition C5H6Cl2O4Si. The effect of pKa values of carboxylic acids on the direction and mechanism of the examined reaction is discussed.

Acyl iodides in organic synthesis: XII. Reactions with organosilicon amines

Reactions were investigated between acyl iodides RCOI (R = Me, Ph) and organosilicon amines of two classes: trimethyl(diethylamino)silane, dimethyl-bis(diethylamino)silane, and hexamethyldisilazane on the one hand, and 3-aminopropyl(triorganyl)silanes H2N(CH2)3SiX3 (X = Et, EtO) on the other hand. The reaction of RCOI with trimethyl(diethylamino)silane Me3SiNEt2 occurred with a cleavage of the Si-N bond and the formation of N,N-diethylacet- or -benzamides and trimethyliodosilane separated in a mixture with hexamethyldisiloxane. At the reaction of acyl iodides RCOI (R = Me, Ph) with dimethyl-bis(diethylamino)silane in the ratio 2:1 in benzene solution both Si-N were ruptured leading to the diethylamide of the corresponding acid and dimethyldiiodosilane. The main product of the reaction of acetyl iodide with hexamethyldisilazane at the molar ratio 2:1 was diacetylimide (MeCO)2NH. This reaction can be recommended as a simple and convenient preparation procedure for diacylimides. The exothermal reaction of the acetyl iodide with 3-aminopropyl(triethyl)- and -(triethoxy)silanes at the molar ratio of the reagents 1:1 without solvent resulted in quaternary ammonium salts, hydroiodides of the corresponding acetylamides I−MeCON+H2(CH2)3SiX3 (X = Et, OEt).

Acyl Iodides in Organic Synthesis: IV. Reaction of Acetyl Iodide with Carboxylic Acids

In contrast to acyl chlorides, reactions of acetyl iodide with monocarboxylic acids follow the exchange pattern to give the corresponding acyl iodides and acetic acid. The reaction attracts interest from the preparative viewpoint as a simple and convenient route to acyl iodides. Acetyl iodide reacts with phthalic acid, yielding acetic acid and phthalic anhydride, while the reaction of acetyl iodide with oxalic acid leads to formation of acetic acid, carbon(II) oxide, and molecular iodine.

Mono- and bis-N-[3-(triorganylsilyl)propyl]guanidines and their derivatives

Organosilicon guanidine derivatives RNHC(=NH)NHCH2CH2CH2Si(OC2H5)3-n (OH)n [R = H, n = 1; R = (CH2)3Si(OC2H5)3, n = 0] were synthesized by condensation of guanidinium carbonate with (3-aminopropyl)triethoxysilane. The products were brought into ether interchange with thiethanolamine and hydrolytic polycondensation.

Uranium(VI) Sorption on Polysilsesquioxanes with Various Organic Functional Groups

Sorption of UO22+ on polysilsesquioxanes with thiourea dioxide, acetamide, phthalimide, and malonamide functional groups was studied.

Acyl iodides in organic synthesis: VIII. Reactions with amino acids

Reactions of acyl iodides RCOI (R=Me, Ph) with glycine, β-alanine, and γ-aminobutyric acid were investigated. The reaction proceeded easily at room temperature without solvent involving both functional groups H2N and COOH. The prevalence of one of the reaction directions depends on the acidity of the amino acid. The more acidic glycine (pКa 2.4) reacts with RCOI affording mainly N-acylated product, whereas β-alanine (pКa 3.60) and especially γ-aminobutyric acid (pКa 4.06) are predominantly involved into exchange iodination furnishing the corresponding aminoacyl iodides.

2-{[3-(triethoxysilyl)propyl]amino}pyridine and derivatives

Abstract2-{[3-(Triethoxysilyl)propyl]amino}pyridine is synthesized by condensation of [3-(triethoxysilyl)propyl]amine with 2-aminopyridine. Its peretherification with triethanolamine leads to 2-[(3-silatranylpropyl)amino]pyridine and hydrolytic copolycondensation with tetraethoxysilane to cross-linked organosilicon copolymer {SiO2·2[O1.5Si(CH2)3NHC6H4N]}n. The latter in the medium of hydrochloric acid behaves as an anionite in respect of anionic chlorocomplexes of gold(III), platinum(IV), palladium(II) and rhodiumIII).