- A convenient method for the generation of a disulfur monoxide equivalent and its reaction with diazoalkanes to yield dithiirane 1-oxides
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Oxidation of elemental sulfur (S8) with dimethyldioxirane (or CF3CO3H) generates a disulfur monoxide equivalent ("S2O"). Yields of "S2O" of 30-40% are obtained from equimolar amounts of S8 and an oxidizing agent. "S2O" reacts with diazoalkanes to give dithiirane 1-oxides [Eq. (1)].
- Ishii, Akihiko,Kawai, Tetsuhiko,Tekura, Kentaro,Oshida, Hideaki,Nakayama, Juzo
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- Initial investigation into the Suzuki-Miyaura vinylation of hindered aryl bromides utilizing potassium vinyltrifluoroborate
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An initial study of the Suzuki-Miyaura cross-coupling of potassium vinyltrifluoroborate (2) and hindered aryl bromides is presented. Coupling of benzyl 3,5-bis(benzyloxy)-4-bromobenzoate (1) leads to a mixture of the desired styrene derivative, and the reduced product.
- Carter, Rhiannon R.,Wyatt, Justin K.
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- Direct Observation of Aryl Gold(I) Carbenes that Undergo Cyclopropanation, C?H Insertion, and Dimerization Reactions
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Mesityl gold(I) carbenes lacking heteroatom stabilization or shielding ancillary ligands have been generated and spectroscopically characterized from chloro(mesityl)methylgold(I) carbenoids bearing JohnPhos-type ligands by chloride abstraction with GaCl3. The aryl carbenes react with PPh3 and alkenes to give stable phosphonium ylides and cyclopropanes, respectively. Oxidation with pyridine N-oxide and intermolecular C?H insertion to cyclohexane have also been observed. In the absence of nucleophiles, a bimolecular reaction, similar to that observed for other metal carbenes, leads to a symmetrical alkene.
- García-Morales, Cristina,Pei, Xiao-Li,Sarria Toro, Juan M.,Echavarren, Antonio M.
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- McMurry coupling of aryl aldehydes and imino pinacol coupling mediated by Ti(O-i-Pr)4/Me3SiCl/Mg reagent
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Ti(O-i-Pr)4/Me3SiCl/Mg reagent mediated McMurry coupling of aryl aldehydes to biaryl olefins at near room temperature. This low valent titanium (LVT) reagent also mediated the coupling of aldimines to 1,2-diamines (imino pinacol coupling).
- Okamoto, Sentaro,He, Jing-Qian,Ohno, Chihaya,Oh-iwa, Yuhji,Kawaguchi, Yuhki
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experimental part
p. 387 - 390
(2010/03/03)
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- Designing systems for one-way trans to cis photoisomerization for solar reactions
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We have examined triplet photosensitized isomerization of sterically crowded derivatives of stilbene, diene, triene and styrene. Under selective triplet sensitization, several such compounds proceeded in the synthetically desirable manner of complete one-
- Zhao, Yao-Peng,Yang, Lan-Ying,Liu, Robert S. H.
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experimental part
p. 837 - 842
(2010/04/23)
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- Suzuki-Miyaura cross-coupling reactions of potassium vinyltrifluoroborate with aryl and heteroaryl electrophiles
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We have previously reported that the palladium-catalyzed cross-coupling reaction of potassium vinyltrifluoroborate with aryl electrophiles proceeds with good yields. Herein, we describe recent progress in optimizing the reaction, as well as outlining the scope and limitations of the reaction. The cross-coupling reaction can generally be effected using 2 mol % of PdCl2 and 6 mol % of PPh3 as a catalyst system in THF/H2O with Cs 2CO3 as a base. Moderate to good yields are obtained in the presence of a variety of functional groups.
- Molander, Gary A.,Brown, Adam R.
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p. 9681 - 9686
(2007/10/03)
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- Laser flash photolysis study of phenylcarbene, o-tolylcarbene and mesitylcarbene
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Laser flash photolysis (LFP, XeCl, 308 nm, 20 ns) of phenyldiazomethane (PDM), o-tolydiazomethane (TDM) and mesitydiazomethane (MDM) produces phenylcarbene (PC), o-tolycarbene (TC) and mesitylcarbene (MSC), respectively. Transient spectra of PC and TC cou
- Admasu, Atnaf,Platz, Matthew S.,Marcinek, Andrzej,Michalak, Jacek,Gudmundsdottir, Anna Dora,Gebicki, Jerzy
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p. 207 - 220
(2007/10/03)
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- Heterodiene cycloadditoins of C2 symmetric 4,5-disubstituted ketene acetals: the nett asymmetric conjugate addition of recyclable acetic ester enolate equivalents to an activated enone
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Heterodiene cycloadditions of 3-formylchromone 2 to a series of ketene acetals 1 derived from C2 symmetric 1,2-diarylethane-1,2-diols are diastereoselective.From (S,S)-1,2-di(o-tolyl)ethane-1,2-diol 6c the major cycloadduct 3c was isolated by crystallization and transformed by acid-catalysed methanolysis into (S)-methyl 4-oxo-3,4-dihydro-2H-1-benzopyran-2-ylacetate 5, together with the original 1,2-diol 6c which could be recycled.The structures of two cyclic carbonates 22a and 22c were determined by X-ray diffraction and used as models in seeking a mechanistic rationale for the stereoselective cycloadditions of the analogous ketene acetals 1a and 1c.
- Wallace, Timothy W.,Wardell, Ian,Li, Ke-Dong,Leeming, Peter,Redhouse, Alan D.,Challand, S. Richard
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p. 2293 - 2308
(2007/10/02)
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- Thioaldehyde S-Oxide (Monosubstituted Sulfines) from Thioacylsilane S-Oxides. Synthesis and Fluorine- and Acid-Induced Z/E Isomerization. 2
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Aromatic and aliphatic, not enethiolizable, thioaldehyde S-oxides (monosubstituted sulfines) are obtained from stereospecific fluorodesilylation of the corresponding thioacylsilane S-oxides with retention of configuration.A detailed investigation on the mechanism of the desilylation, as well as of the acid and fluoride ion induced Z/E interconversion has been performed.
- Barbaro, G.,Battaglia, A.,Giorgianni, P.,Bonini, B. F.,Maccagnani, G.,Zani, P.
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p. 3744 - 3748
(2007/10/02)
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- RHODIUM ION CATALYZED DECOMPOSITION OF ARYLDIAZOALKANES
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Aryldiazomethanes are converted by rhodium(II)acetate and iodorhodium(III) tetraphenylporphyrin to cis- rather than trans-1,2-diarylethylenes.Secondary aryldiazoalkanes react with rhodium(II) acetate to give azines.
- Shankar, B.K. Ravi,Shechter, Harold
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p. 2277 - 2280
(2007/10/02)
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