20841-46-7Relevant academic research and scientific papers
Catalytic, Enantioselective Sulfenylation of Ketone-Derived Enoxysilanes
Denmark, Scott E.,Rossi, Sergio,Webster, Matthew P.,Wang, Hao
, p. 13016 - 13028 (2015/09/15)
A catalytic, enantioselective, Lewis base-catalyzed α-sulfenylation of silyl enol ethers has been developed. To avoid acidic hydrolysis of the silyl enol ether substrates, a sulfenylating agent that did not require additional Br?nsted acid activation, namely N-phenylthiosaccharin, was developed. Three classes of Lewis bases - tertiary amines, sulfides, and selenophosphoramides - were identified as active catalysts for the α-sulfenylation reaction. Among a wide variety of chiral Lewis bases in all three classes, only chiral selenophosphoramides afforded α-phenylthio ketones in generally high yield and with good enantioselectivity. The selectivity of the reaction does not depend on the size of the silyl group but is highly sensitive to the double bond geometry and the bulk of the substituents on the double bond. The most selective substrates are those containing a geminal bulky substituent on the enoxysilane. Computational analysis revealed that the enantioselectivity arises from an intriguing interplay among sterically guided approach, distortion energy, and orbital interactions.
A new sulfenylation reagent, 3-phenylsulfenyl-2-(N- cyanoimino)thiazolidine, and its optically active version
Tanaka,Azuma,Fang,Uchida,Iwata,Ishida,In,Maezaki
, p. 33 - 36 (2007/10/03)
We have developed a new sulfenylation reagent, 3-phenylsulfenyl-2-(N- cyanoimino)thiazolidine 3, that is readily available and stable upon storage. Compound 3 easily reacts with amines or thiols to give the corresponding sulfenamides or asymmetrical disulfides in excellent yields. It was also found that the α-sulfenylation reaction of carbonyl compounds with 3 proceeds smoothly. Furthermore, optically active 4-diphenylmethyl derivative 4 was synthesized as an asymmetric sulfenylation reagent, which realized 96% e.e. upon α-sulfenylation of a cyclic β-keto ester.
The Desulfurization of Polynuclear Aromatic Sulfur Compounds with a Raney Nickel
Nagai, Masatoshi,Urimoto, Hideo,Uetake, Kazuya,Sakikawa, Noriyuki,Gonzalez, Richard D.
, p. 557 - 562 (2007/10/02)
The mechanism of the desufulization of the polynuclear thiophene compounds with a Raney nickel was studied in ethanol at atmospheric pressure and from 0 to 73.3 degC.The desulfurization rate was initially fast but reached zero in about 30 minutes.The major products were biphenyl in the desulfurization of dibenzothiophene (1), 1-phenylnaphthalene in the desulfurization of benzonaphthothiophene (2), and 2-phenylnaphthalene in the reaction of benzonaphthothiophene (3) and benzonaphthothiophene (4).The desulfurization extent for the four compounds decreased in this sequence: 3>1>2>4.The extent of the desulfurization of the polynuclear thiophene compound was not related to the reaction indices, Fr(E), Fr(N), and Fr(R), of the sulfur atom of the compounds, which were calculated by using a simple Hueckel theory; rather, it was related to both the free valence and the ?-electron density.Therefore, the polynuclear thiophene compounds were considered to adsorb on a Raney nickel through the free-electron pair of the sulfur atom; consequently, the adsorption led to the C-S bond scission.
Synthesis of 5,6,6a,7,7a,12a-Hexahydro-4H-benzobenzothienoquinolines and of 8-Phenyl-2,3,7,8,9,9a-hexahydro-1H-benzoquinolines
Copp, Frederick C.,Franzmann, Karl W.,Gilmore, Jeremy,Whalley, W. Basil
, p. 909 - 914 (2007/10/02)
Demethylation of 1-(3-benzothienylmethyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline (1; R=H) gives two diastereoisomeric 1,2-dihydroxy-5,6,6a,7,7a,12a-hexahydro-4H-benzobenzothienoquinolines (4; R=H).Desulphurisation of their N-acetyl-di
