Regiospecific conversion of alkenyl sulphides to α-sulphenylated carbonyl compounds by oxygenation in the presence of thiophenol
作者:Jun-ichi Yoshida、Shogo Nakatani、Sachihiko Isoe
DOI:10.1039/c39880001468
日期:——
Regiospecificconversion of alkenyl sulphides to α-sulphenylated carbonylcompounds was achieved by oxygenation in the presence of thiophenol; electrolysis was found to be quite effective for initiation of the reaction.
Diastereoselection during 1,2-Addition of the Allylindium Reagent to α-Thia and α-Amino Aldehydes in Aqueous and Organic Solvents
作者:Leo A. Paquette、Thomas M. Mitzel、Methvin B. Isaac、Curtis F. Crasto、William W. Schomer
DOI:10.1021/jo970274d
日期:1997.6.1
The stereochemistry of the indium-promoted reaction of allyl bromide with alpha-thia (PhS and MeS), disubstituted alpha-amino (Bn2N, Me2N, isoindolyl), and protected alpha-amino aldehydes (Ac and Boc) in water has been evaluated. The reactions involving the sulfur derivatives are minimally diastereoselective, indicating that the allylindium reagent is not thiophilic. Chelation is not observed and pi-facial discrimination is achieved via Felkin-Ahn transition states under the steric control of the substituents. The Garner aldehyde is also anti-diastereoselective. Interestingly, N-acetylmannosamine is appreciably responsive to chelation control and is capable of generating 90% of the syn beta-amino alcohol when reacted in a 0.5 M NH4Cl solution. While the alpha-dibenzylamino substituent is too bulky to enter into complexation, the alpha-dimethylamino group is not and can lead to high levels (99%) of syn diastereomer. The size of other neighboring substituents does have an impact on pi-facial discrimination in these systems and can erode the stereoselectivity accordingly.
Electroinitiated oxygenation of alkenyl sulfides and alkynes in the presence of thiophenol
作者:Junichi Yoshida、Shogo Nakatani、Sachihiko Isoe
DOI:10.1021/jo00070a021
日期:1993.8
Electrolysis of alkenyl sulfides in the presence of thiophenol with bubbling of molecular oxygen gave the corresponding alpha-(phenylthio) carbonyl compounds with the consumption of a catalytic amount of electricity. An electroinitiated radical chain mechanism has been proposed. The reaction also took place without electrochemical initiation, but much (5-50 times) longer reaction time was required for the completion of the reaction. The potential utility of the present reaction in organic synthesis is demonstrated by the net 1,2-transposition of a phenylthio group and a carbonyl group. The electroinitiated oxygenation of ketene dithioacetals also proceeded smoothly to give the corresponding alpha-(phenylthio) thiol esters. It was also found that the electroinitiated oxygenation of alkynes in the presence of thiophenol gave alpha-(phenylthio) carbonyl compounds. A mechanism involving the initial formation of alkenyl sulfides has been proposed.
SATO, TSUNEO;OKAZAKI, HIROSHI;OTERA, JUNZO;NOZAKI, HITOSI, J. AMER. CHEM. SOC., 110,(1988) N 15, 5209-5211
Synthese de composes dicarbonyles-1,4 par reaction de Wittig sur des aldehydes, la methode peut etre etendue a la synthese de composes tricarbonyles-1,4,7
Synthese de composes dicarbonyles-1,4 par 反应 de Wittig sur des aldehydes, la methode peut etre etendue a la synthese de composes tricarbonyles-1,4,7