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: 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 (pК_a 2.4) reacts with RCOI affording mainly N-acylated product, whereas β-alanine (pК _a 3.60) and especially γ-aminobutyric acid (pК_a 4.06) are predominantly involved into exchange iodination furnishing the corresponding aminoacyl iodides.     

Acyl iodides in organic synthesis. Reaction of acyl iodides with triphenylethoxy- and triphenylhydroxysilane

The reaction of triphenylethoxysilane with acetyl or benzoyl iodide led to the formation of triphenyliodosilane and ethyl ester of the corresponding carboxylic acid. Triphenyliodosilane formed also in the reaction of triphenylsilanol with benzoyl iodide. These reactions comprise the new simplest method of preparation of the triphenyliodosilane (yield over 60%). The reaction product of triphenylhydroxysilane and acetyl iodide is triphenylacetoxysilane. The reactions of the studied acyl iodides with triphenylhydroxysilane is the first example of different regioselectivity of acetyl iodide and benzoyl iodide in reactions with organic and organoelemental compounds.     

Acyl iodides in organic synthesis: XIII. Reaction of acyl iodides with nitrogen-containing heteroaromatic compounds

Reactions of acetyl iodide with pyridine at room temperature and with quinoline both at 20–25°C and on cooling to −50°C involve dehydrohalogenation of acetyl iodide with formation of ketene and pyridinium or quinolinium iodides. The reaction of acetyl iodide with pyridine at −5 to −50°C led to the formation of N-acetylpyridinium iodide. Benzoyl iodide reacted with both pyridine and quinoline at both −50°C and at 20–25°C to form stable N-benzoylpyridinium and N-benzoylquinolinium iodides. The reaction of pyrrole with acetyl iodide under analogous conditions was accompanied by polymerization.     

Acyl iodides in organic synthesis: X. Reactions with triorganylsilanes and triphenylgermane

Reaction of acyl iodides RCOI (R = Me, Ph) with triorganylsilanes R′₂R″SiH in toluene gives 50–60% of the corresponding triorganyliodosilanes R′₂R″SiI. Triethylsilane reacts with the same acyl iodides under solvent-free conditions to afford the corresponding aldehyde and triethyliodosilane as primary products. Triethyliodosilane undergoes subsequent transformations into hexaethyldisiloxane and triethyl(acyloxy)silane Et₃SiOCOR (R = Me, Ph). Reactions of acyl iodides RCOI (R = Me, Ph) with triphenylgermane in the absence of a solvent lead to formation of iodo(triphenyl)germane in more than 90% yield.     

Acyl iodides in organic synthesis. Reaction of acetyl iodide with thiols

The direction of reactions of acetyl iodide with aliphatic, aromatic, and heterocyclic thiols is determined by the thiol acidity and steric factors. Acetyl iodide reacted with aliphatic thiols, including trialkylsilylsubstituted derivatives R(CH₂) _n SH (R = Me, n = 3; R = Me₃Si, n = 3; R = Et₃Si, n = 2), to give the corresponding ethanethioates R(CH₂) _n SCOMe. Benzenethiol was oxidized with acetyl iodide to diphenyl disulfide. The reaction of acetyl iodide with 2-sulfanylethanol afforded 2-(2-iodoethyldisulfanyl)ethyl acetate as a result of three consecutive-parallel processes: acylation, iodination, and oxidation of the initial compound. 1,3-Benzothiazole-2-thiol reacted with acetyl iodide only at the nitrogen atom to give quaternary salt, whereas the SH group remained intact.     

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 and organoelement chemistry

This review is focused on our and literature data on reactions of acyl iodides RC(O)I with organic (alcohols, ethers, esters, carboxylic acids, amino acids, tertiary amines, nitrogen heterocycles, carbamides, thiocarbamides, and thiols) and organoelement compounds (alkoxy silanes, siloxanes, silylamines, silazanes, silicon-containing amines, and ethynyl silanes, germanes, and stannanes). Photolysis of acyl iodides in arene medium yields a-diketones, products of photochemical Friedel-Crafts acylation and iodination of arenes, and polyarylenation.     

Acyl iodides in organic synthesis. reaction of acetyl iodide with Dialkyl sulfides and disulfides

Reactions of acetyl iodide with dialkyl and dialkenyl sulfides RSR (R = Et, Bu, CH₂=CH, CH₂=CHCH₂) and with disulfides RSSR (R = Pr, C₆H₁₃, PhCH₂) were studied. Dialkyl sulfides reacted with MeCOI to give the corresponding alkyl ethanethioates and alkyl iodides as a result of cleavage of the S-C bond. The reactions of acetyl iodide with divinyl and diallyl sulfides involved addition across the double bond and subsequent polymerization of 1-alkenylsulfanyl-2(3)-iodoalkyl methyl ketones. Dialkyl disulfides RSSR (R = Pr, C₆H₁₃) and dibenzyl disulfide reacted with acetyl iodide via cleavage of the S-S bond to produce the corresponding ethanethioates and organylsulfenyl iodides. The latter underwent disproportionation to form the initial disulfide and molecular iodine.     

Acyl iodides in organic synthesis: VII. Reactions with trialkyl(alkynyl)silanes,-germanes, and-stannanes

Reactions of acyl iodides R¹COI (R¹=Me, Ph) with trialkyl(alkynyl)silanes,-germanes, and stannanes (R²C≡CMR ₃ ³ ; M=Si, Ge, Sn) were studied. Acyl iodides reacted with the germanium and tin derivatives with cleavage of the M-C_sp bond and formation of the corresponding trialkyl(iodo)germanes and-stannanes R ₃ ³ MI (M=Ge, Sn) and alkynyl ketones R¹C(O)C≡CR² and R¹C(O)C≡CC(O)R¹. By contrast, the reaction of acetyl iodide with ethynyl(trimethyl)silane gave only a small amount of 1,2-diiodovinyl(trimethyl) silance as a result of iodine addition at the triple bond. Bis(trimethylsilyl)ethyne failed to react with acetyl iodide.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Palladium catalysed 3-component cascade synthesis of bis(2-arylallyl) tertiary amines from aryl iodides,allene and primary amines

A 3-component cascade synthesis of bis(2-arylallyl) tertiary amines from aryl iodide, allene and primary aliphatic amines is described; chiral amines give analogous products with no detectable racemisation; mixtures of two different aryl iodides can be utilised to give the mixed tertiary amines as the sole, or major, product; the reaction is sensitive to stereoelectronic effects which lead to mono(2-arylallyl) secondary amines.     

Rapid reductive-carboxylation of secondary amines. One pot synthesis of tertiary N-methylated amines

Various tertiary N-methylated amines were synthesized by using a new reductive-carboxylation approach. Secondary amines, on carboxylation with carbon dioxide under moderate reaction conditions, afforded their corresponding carbamate esters, which, on $\text{in situ}$ lithium aluminum hydride reduction, gave desired tertiary N-methylated amines in high yield.     

C---C bond cleavage in the interaction of anthraquinone triplet with tertiary alcohols and tertiary butylbenzene

In the photochemical reaction of anthraquinone triplet with both tertiary alcohols and tert.Bu-benzene in C₆H₆ at λ 334 nm not only C---H (or O---H) bonds but C---C bonds are also broken, yielding CH₃, and R₁C(R₂)OH (or C₆H₅C(CH₃)₂) radicals, at room temperature.     

Mechanism of phosphorus-carbon bond cleavage by lithium in tertiary phosphines. An optimized synthesis of 1,2-Bis(phenylphosphino)ethane

Conditions influencing the extent of P-C(aryl) vs P-C(alkyl) bond cleavage in the reaction of Ph(2)P(CH(2))(2)PPh(2) with lithium in THF have been investigated. The results complement and elucidate earlier work; they indicate that the mechanism of P-C bond cleavage in tertiary phosphines of this type involves a thermodynamic equilibrium between P-C(aryl) and P-C(alkyl) cleaved radicals and anions, followed by reaction and stabilization of these as lithium salts. The addition of water to the reaction mixture causes a reestablishment of the cleavage equilibrium prior to the formation of the secondary phosphines. A mechanism involving competitive release of leaving groups as the thermodynamically most stable anion or radical has been proposed. The preparation of (R, R)-(+/-)/(R, S)-PhP(H)(CH(2))(2)P(H)Ph by this route has been optimized.     

Unusual palladium-catalyzed silaboration of allenes using organic iodides as initiators: mechanism and application

A highly regio- and stereoselective method for the synthesis of various 2-silylallylboronates 7 from allenes 1 and 2-(dimethylphenylsilanyl)-4,4,5,5-tetramethyl[1,3,2]dioxaborolane (5) catalyzed by palladium complexes and initiated by organic iodides is described. Treatment of monosubstituted aryl and alkylallenes RCH=C=CH(2) (1a-m) and 1,1-dimethylallene (1n) with borylsilane 5 in the presence of Pd(dba)(2) (5 mol %) and organic iodide 3a (10 mol %) afforded the corresponding silaboration products 7a-n in moderate to excellent yields. This catalytic silaboration is totally regioselective with the silyl group of 5adding to the central carbon and the boryl group to the unsubstituted terminal carbon of allene. Furthermore, the reactions show very high E stereoselectivity with the Z/E ratios lying in the range from 1/99 to 7/93. In the absence of an organic iodide, silaboration of 1 with 5 still proceeds, but gives products having completely different regiochemistry as that of 7. The silaboration chemistry can be applied to the synthesis of homoallylic alcohols. Treatment of allenes (1) with borylsilane 5 and aldehydes 14 in the presence of Pd(dba)(2) (5 mol %) and 3a (10 mol %) at 80 degrees C in ethyl acetate for 5 h afforded homoallylic alcohols 15a-p in one pot in good to excellent yields, with exceedingly high syn selectivity (>93%). Mechanistic pathways involving an unusual palladium-catalyzed three-component assembling reaction of dimethylphenylsilyl iodide, allene 1, and borylsilane 5 were proposed to account for these catalytic reactions.