67274-35-5Relevant academic research and scientific papers
Sequential one-pot addition of excess aryl-grignard reagents and electrophiles to O-alkyl thioformates
Murai, Toshiaki,Morikawa, Kenta,Maruyama, Toshifumi
, p. 13112 - 13119 (2013/10/01)
The sequential addition of aromatic Grignard reagents to O-alkyl thioformates proceeded to completion within 30s to give aryl benzylic sulfanes in good yields. This reaction may begin with the nucleophilic attack of the Grignard reagent onto the carbon atom of the O-alkyl thioformates, followed by the elimination of ROMgBr to generate aromatic thioaldehydes, which then react with a second molecule of the Grignard reagent at the sulfur atom to form arylsulfanyl benzylic Grignard reagents. To confirm the generation of aromatic thioaldehydes, the reaction between O-alkyl thioformates and phenyl Grignard reagent was carried out in the presence of cyclopentadiene. As a result, hetero-Diels-Alder adducts of the thioaldehyde and the diene were formed. The treatment of a mixture of the thioformate and phenyl Grignard reagent with iodine gave 1,2-bis(phenylsulfanyl)-1,2-diphenyl ethane as a product, which indicated the formation of arylsulfanyl benzylic Grignard reagents in the reaction mixture. When electrophiles were added to the Grignard reagents that were generated insitu, four-component coupling products, that is, O-alkyl thioformates, two molecules of Grignard reagents, and electrophiles, were obtained in moderate-to-good yields. The use of silyl chloride or allylic bromides gave the adducts within 5min, whereas the reaction with benzylic halides required more than 30min. The addition to carbonyl compounds was complete within 1min and the use of lithium bromide as an additive enhanced the yields of the four-component coupling products. Finally, oxiranes and imines also participated in the coupling reaction. Into the melting pot: The addition of excess aryl Grignard reagents and electrophiles to O-alkyl thioformates gives aryl sulfanes through four-component coupling reactions (see scheme). These reactions may involve the formation of aromatic thioaldehydes and aryl-benzylic Grignard reagents as intermediates. For addition to carbonyl compounds, the use of lithium halides as an additive enhanced the efficiency of the reaction. Copyright
Substituent effect on benzylic lithiation of sulfides. Synthesis of diboronic acids derived from aryl-alkyl sulfides
Da?browski, Marek,Durka, Krzysztof,Kli?, Tomasz,Serwatowski, Janusz,Wo?niak, Krzysztof
, p. 3159 - 3166 (2013/05/08)
The relative benzylic deprotonation rate constants of aryl-benzyl sulfides have been measured and the obtained values were compared with the substituent constants using the Hammett equation and with deprotonation Gibbs energies calculated on B3LYP/aug-cc-pVDZ level. The deprotonation rate depends on the stabilization of the negative charge, which is spread over the benzene ring. The series of brominated alkyl-aryl sulfides was di-lithiated by Br/Li exchange using t-BuLi and the obtained organolithium compounds were converted into the respective diboronic acids. Lithiation of aryl-benzyl sulfides containing a bromine atom in the para or ortho positions occurs selectively, however for the meta derivative, the process is plagued by competitive benzylic deprotonation. This fact can be rationalized on the basis of the obtained relative deprotonation rate constants. The X-ray analysis of bis-(2- dihydroxyborylphenylthio)methane revealed the existence of three different structural motifs, which stabilize the structure by hydrogen bonding formation.
Sulfur radical cations. Kinetic and product study of the photoinduced fragmentation reactions of (phenylsulfanylalkyl)trimethylsilanes and phenylsulfanylacetic acid radical cations
Baciocchi, Enrico,Giacco, Tiziana Del,Elisei, Fausto,Lapi, Andrea
, p. 853 - 860 (2007/10/03)
Laser and steady-state photolysis, sensitized by NMQ+, of PhSCH(R)X 1-4 (R = H, Ph; X =SiMe3, CO2H) was carried out in CH3CN. The formation of 1+.-4+. was clearly shown. All radical cations undergo a fast first-order fragmentation reaction involving C-Si bond cleavage with 1+. and 2+. and C-C bond cleavage with 3+. and 4+.. The desilylation reaction of 1+. and 2+. was nucleophilically assisted, and the decarboxylation rates of 3+. and 4+. increased in the presence of H2O. A deuterium kinetic isotope effect of 2.0 was observed when H2O was replaced by D2O. Pyridines too were found to accelerate the decarboxylation rate of 3+. and 4 +.. The rate increase, however, was not a linear function of the base concentration, but a plateau was reached. A fast and reversible formation of a H-bonded complex between the radical cation and the base is suggested, which undergoes C-C bond cleavage. It is probable that the H-bond complex undergoes first a rate determining proton-coupled electron transfer forming a carboxyl radical that then loses CO2. The steady-state photolysis study showed that PhSCH3 was the exclusive product formed from 1 and 3 whereas [PhS(Ph)CH-]2 was the only product with 3 and 4.
Studies on the reactive species in fluoride-mediated carbon-carbon bond-forming reactions: Carbanion formation by desilylation with fluoride and enolates
Biddle, Margaret M.,Reich, Hans J.
, p. 4031 - 4039 (2007/10/03)
The reactive species in fluoride-mediated carbon-carbon bond-forming reactions was investigated. The regio- and diastereoselectivities of silanes reacting with cyclohexenone in the presence of a catalytic amount of fluoride was compared to the reactivity of analogous solvent-separated lithium ion pairs. Closely analogous behavior was observed, showing that carbanions and not siliconate complexes are the reactive species in the fluoride-catalyzed reactions. Spectroscopic investigations unambiguously show that phenylthiobenzyl anion will form by reaction of silane with tris(dimethylamino)sulfonium difluorotrimethylsilicate (TASF) or crypt[2.1.1]-solvated lithium enolates. The catalytic cycle runs smoothly with the crypt[2.1.1] complex of α-(phenylthio)benzyllithium as the initiator and enolate as the carrier of the desilylation reaction.
Transformation of α-assisted carbanions into the corresponding trimethylsiloxy derivatives using bis(trimethylsilyl)peroxide
Dembech,Guerrini,Ricci,Seconi,Taddei
, p. 2999 - 3006 (2007/10/02)
The reaction of bis(trimethylsilyl)peroxide with tlithium derivatives of sulphides and nitriles is reported to give the corresponding O-trimethylsilyl hemithioacetals and cyanohydrins. From these products the carbonyl function can be exposed in acidic media or in the presence of fluoride ions. This methodology provides an attractive route to transform a CH2-X group (X = PhS, MeS or CN) into the corresponding CHO, allowing the preparation of aldehydes that can be considered difficult to prepare such as, for example, formyltrimethylsilane which was generated and trapped in situ using a Wittig reaction.
REACTION OF TRIMETHYLSILANE WITH ARENES AND ALK-1-ENES IN THE PRESENCE OF LEWIS ACID
Han, Dong Il,Oh, Dong Young
, p. 2213 - 2218 (2007/10/02)
trimethylsilane reacted with arenes and alk-1-enes in the presence of a Lewis acid to give the Friedel-Crafts product and the ene product, respectively.
The Synthesis of Ketones via α-Silyl Sulphides
Ager, David J.
, p. 195 - 204 (2007/10/02)
α-Phenylthiosilanes (2) have been prepared by alkylation of the anion (4) derived from the 1-phenylthio-1-trimethylsilylalkane (1).These anions (4) have benn prepared by a variety of methods including, direct deprotonation of (1), displacement of a phenylthio group by lithium naphthalenide addition of an alkyl-lithium to 1-phenylthio-1-trimethylsilylethene (7), and transmetallation of a tributylstannyl moiety.The formation of an alkyl-lithium by reaction of lithium naphthalenide with a phenyl sulphide provided an additional route to (2) from bis(phenylthio)acetals (8).An alternative path to the α-phenylthiosilanes (2) was to reduce the corresponding α-phenylsulphonylsilane (15); these, in turn, being readily available from alkylation or silylation of α-sulphonyl anions.The α-phenylthiosilanes (2) were converted into the O-trimethylsilylphenylthioacetal (18) by the sila-Pummerer rearrangement, although this was complicated by vinyl sulphide (20) formation in certain cases.Subsequent hydrolysis of (18) and (20) gave the ketone (3).
Synthesis of Aldehydes from Phenylthiotrimethylsilylmethane
Ager, David J.
, p. 1131 - 1136 (2007/10/02)
Phenylthiotrimethylsilylmethyl-lithium (4) reacts with alkyl halides to give 1-phenylthio-1-trimethylsilylalkanes (5), which can also be prepared by the addition of alkyl-lithium to 1-phenylthio-1-trimethylsilylethene (8), or from bis(phenylthio)acetals (11).The 1-phenylthio-1-trimethylsilylalkanes (5) can be converted into the corresponding aldehyde (15) by oxidation to the sulphoxide (13), thermal rearrangement, and hydrolysis of the resultant O-silyl thioacetal (14).
Preparation of sulfines by alkylidenation of sulfur dioxide using α-silyl carbanions
Porskamp, P. A. T. W.,Leij, M. van der,Lammerink, B. H. M.,Zwanenburg, B.
, p. 400 - 404 (2007/10/02)
The synthesis of sulfines 4 from a series of active methylene compounds is described.Deprotonation, followed by silylation, gives the trimethylsilyl compounds 2.Subsequent deprotonation to α-silyl carbanions and treatment with an excess of sulfur dioxide
A NEW METHOD FOR PREPARING 1-PHENYLTHIO-1-TRIMETHYLSILYLALKANES: THE PREPARATION OF α-SILYLCARBANIONS AND OLEFINS.
Ager, David J.
, p. 2923 - 2926 (2007/10/02)
1-Phenylthio-1-trimethylsilylalkanes(1) are prepared in high yield from 1,1-bis(phenylthio)acetals(2) by reaction with lithium naphthalenide(3) followed by chlorotrimethylsilane. α-Silylcarbanions are formed from the alkanes(1) and lithium naphthalenide(3).Subsequent reaction with carbonyl compounds gave the olefins(4) via the Peterson reaction.
