Investigation of steric and electronic effects in the copper-catalysed asymmetric oxidation of sulfides
作者:Graham E. O'Mahony、Kevin S. Eccles、Robin E. Morrison、Alan Ford、Simon E. Lawrence、Anita R. Maguire
DOI:10.1016/j.tet.2013.08.063
日期:2013.11
in the copper-catalysed asymmetricoxidation of aryl benzyl, aryl alkyl and alkyl benzyl sulfides have been investigated. The presence of an aryl group directly attached to the sulfur is essential to afford sulfoxides with high enantioselectivities, with up to 97% ee for 2-naphthyl benzyl sulfoxide, the highest enantioselectivity achieved to date for copper-catalysed asymmetric sulfoxidation. In contrast
The first catalytic α-alkylation reaction of benzyl sulfides and 1,3-dithianes with styrenes and conjugated dienes was developed under mild conditions by using a readily available Brønsted base potassium bis(trimethylsilyl)amide (KHMDS) as catalyst. The reaction displayed good functional group tolerance, high efficiency, and excellent chemoselectivity. A series of desired alkylation products were obtained
Photochemical, Metal‐Free Sigmatropic Rearrangement Reactions of Sulfur Ylides
作者:Zhen Yang、Yujing Guo、Rene M. Koenigs
DOI:10.1002/chem.201900597
日期:2019.5.10
Sigmatropic rearrangement reactions constitute one of the most fundamental reactions of carbenes. While state‐of‐the‐art synthetic methods require the use of expensive precious metal catalysts, the application of visible light for the photolysis of α‐aryldiazoacetates is much less investigated and provides an operationally simple entry to carbenes under mild reaction conditions. Herein, we report on
A comparative study of Cu(II)-assisted vs Cu(II)-free chalcogenation on benzyl and 2°/3°-cycloalkyl moieties
作者:SANTOSH K SAHOO
DOI:10.1007/s12039-015-0981-0
日期:2015.12
A relative synthetic strategy toward intermolecular oxidative C −Chalcogen bond formation of alkanes has been illustrated using both Cu(II) assisted vs Cu(II) free conditions. This led to construction of a comparative study of hydrocarbon benzylic and 2∘/ 3∘-cycloalkyl moieties bond sulfenylation and selenation protocol by the chalcogen sources, particularly sulfur and selenium, respectively. In addition, this protocol disclosed the auspicious formation of sp3 C−S coupling products over leading the sp3 C−N coupling products by using 2-mercaptobenzothiazole (MBT) substrates.
Halogen–lithium exchange versus deprotonation: regioselective mono- and dilithiation of aryl benzyl sulfides. A simple approach to α,2-dilithiotoluene equivalents
reactions between aryl benzyl sulfides and alkyllithiums were investigated. The resultant mono- and dilithiated intermediates were converted into the corresponding aldehydes and boronic, or carboxylic acids in good yields. It was found that diethyl ether stabilizes the ortho-lithiated compounds toward isomerisation to the benzylic derivatives. The process occurs easily in THF at low temperature and is