67274-35-5Relevant articles and documents
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
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.
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.
