Studies on the Stereoselective Methylation of α-Sulfinyl Carbanions Generated from Three Isomeric Pyridylmethyl<i>p</i>-Tolyl Sulfoxides and Benzyl 2-Pyridyl Sulfoxide
A high stereoselectivity in the methylation of 2-pyridylmethyl p-tolyl sulfoxide (2a) with lithium diisopropylamide and iodomethane was observed at low temperature. The chelation of Li+ by both the nitrogen atom in the pyridine ring and the sulfinyl oxygen atom in 2a promotes the stereoselectivity as compared with isomeric sulfoxides.
Chiral non-racemic α-substitutedsulfoxides were reacted with O-silylatedketeneacetal in the presence of a catalytic amount of ZnI2 in THF to give chiral non-racemic α-siloxysulfides in >99% ee. This is the highest enantioselectivity reported to date for the Pummerer reaction.
Synthesis of new optically active sulfoxides with chelating properties
作者:Kai - U. Baldenius、Henri B. Kagan
DOI:10.1016/0957-4166(90)80010-v
日期:1990.1
2-pyridinylmethyl sulfoxides and β-imino sulfoxides was sought. The latter were obtained in tautomeric mixtures with their enamines by condensation of opticallyactive β-keto sulfoxides with primary amines. 2-Pyridinylmethyl sulfoxides were synthesized by sulfinate substitution. Titanium catalysed oxidation gave good results for the synthesis of (+)-8-(methylsulfinyl)quinoline from the corresponding
Role of Heterocycles on the Stereoselective Reactions of a-Sulfinyl Carbanions Using Optically Active 2-Pyridylmethyl p-Tolyl and 2-(N-Methylimidazolyl)methyl p-Toyl Sulfoxides with Aldehydes
作者:Naomichi Furukawa、Takahiro Sagae、Satoshi Ogawa
DOI:10.3987/com-91-5691
日期:——
Optically active 2-pyridylmethyl p-tolyl (1) and 2-(N-methylimidazolyl) methyl p-tolyl sulfoxides (2) were synthesized and the reactions of their chiral alpha-sulfinyl carbanions with aldehydes afforded stereoselectively the condensation products. The absolute configurations of the products were determined by x-ray crystallographic analysis and chemical reactions. The mechanism for the reactions is described.
FURUKAWA, NAOMICHI;HOSONO, ERI;FUJIHARA, HISASHI;OGAWA, SATOSHI, BULL. CHEM. SOC. JAP., 63,(1990) N, C. 461-465