- Stereoselective selenium catalyzed dihydroxylation and hydroxymethoxylation of alkenes
-
The selenium atom of the selenocysteine plays a crucial role in the reduction of peroxides. Herein we showed that, in the absence of a thiol cofactor, the same aminoacid efficiently catalyzed the dihydroxylation of carbon-carbon double bonds leading to the stereoselective formation of 1,2-diols at room temperature and in on water conditions. Alternatively, in the presence of methanol, the corresponding β-methoxyalcohol can be prepared. The stereoselectivity of the reaction will be discussed and NMR evidences of the actual catalyst are here reported.
- Santi, Claudio,Di Lorenzo, Rosalia,Tidei, Caterina,Bagnoli, Luana,Wirth, Thomas
-
p. 10530 - 10535,6
(2012/12/12)
-
- Diastereo and enantioselective synthesis of 1,2-diols promoted by electrophilic selenium reagents
-
Here we report the first example in which the phenylseleno group is directly substituted by a hydroxy function. The reaction is promoted by the PhSeOSO3H generated "in situ" by oxidation of (PhSe)2 with (NH4)2S2O8 at reflux in a 3:1 mixture of MeCN-H2O. I
- Santi,Tiecco,Testaferri,Tomassini,Santoro,Bizzoca
-
body text
p. 956 - 960
(2009/04/06)
-
- Hydrogenation en phase liquide sur Pd/C de derives mono et disubstitues du limonene
-
Various derivatives of limonene, either monosubstituted: cis and trans-β-terpineols, (+) neodihydrocarveol, (-) isopulegol, or disubstituted: (+)-trans-N,N-2-dimethylamino-8-trans-p-menthene-1-ol, (+)-N,N-1-dimethylaminoneodihydrocarveol and (+)-trans-N,N-2-dimethylamino-8-cis-p-menthene-1-ol, have been hydrogenated on Pd/C or Adams PtO2 at 25 deg C and under a pressure of 1 atm in ether.With PtO2 the only product obtained has the same configuration as the starting material.On the opposite, due to its isomerising character, Pd/C leads to a mixture of two stereoisomers by racemisation of the asymmetric carbon at position 4 through migration of the exocyclic isopropenyl double bond.In the case of (+) neohydrocarvomenthone (4R) the double bond enters the ring, and so (+) carvomenthone (4R) and (-) isocarvomenthone (4S) are obtained.
- Pavia, Andre Armand,Geneste, Patrick,Olive, Jean-Louis
-
-