Nucleophilic addition reactions of soft carbon nucleophiles to nitrones in a flow microreactor are reported for the first time. Under microflow conditions at 30 to 0 °C, a range of nitrones can be efficiently transformed into the corresponding oxyiminium ions by reaction with either acyl halides or trialkylsilyl triflates. These can subsequently undergo the addition of nucleophiles including allyltributylstannane
首次报道了在流动微反应器中软碳亲核试剂与硝酮的亲核加成反应。在 30 至 0 °C 的微流条件下,通过与酰卤或三烷基甲硅烷基三氟甲磺酸酯反应,可以将一系列硝酮有效地转化为相应的氧亚胺离子。这些随后可以添加亲核试剂,包括烯丙基三丁基锡烷、烯酮甲基叔丁基二甲基甲硅烷基乙缩醛和 N-甲硅烷基烯酮亚胺,以高产率提供相应的加合物;由于不希望有的副反应,在类似温度下在分批条件下的此类反应导致较低的产率。
Catalytic Asymmetric Addition Reaction of Dialkylzinc to Nitrone Utilizing Tartaric Acid Ester as a Chiral Auxiliary
The catalytic asymmetric addition reaction of dialkylzinc to carbon-nitrogen double bond in 3,4-dihydroisoquinoline N-oxide derivatives was achieved by utilizing a catalytic amount of dicyclopentyl (R,R)-tartrate to afford the corresponding (S)-hydroxylamines in high optical yields up to 94% ee.
The catalytic asymmetric addition of dialkylzinc to a carbon-nitrogen double bond in 3,4-dihydroisoquinoline N-oxides was achieved by utilizing a catalytic amount of 2-magnesium 3-zinc salt of dicyclopentyl (R,R)-tartrate to afford (S)-1-alkyl-2-hydroxy-1,2,3,4-tetrahydroisoquinolines. In order to realize higher enantioselectivity, it was crucial to add the nitrones slowly into dialkylzinc in the presence
describes the development of a new variant of stereoselective strain-release driven reactions (formal homo [3 + 2] dipolarcycloadditions) which utilize housane (1) to construct functionalized amino alcohols and pyridine-substituted cyclopentanes in two to three steps from simple and easily available building blocks (nitrones and pyridine N-oxides respectively).
Methyltrioxorhenium-Catalyzed Oxidation of Secondary and Primary Amines with Hydrogen Peroxide
作者:Shigekazu Yamazaki
DOI:10.1246/bcsj.70.877
日期:1997.4
The methyltrioxorhenium-catalyzed oxidation of secondaryamines and primaryamines with hydrogen peroxide has been carried out. The oxidation of secondaryamines afforded nitrones in good-to-excellent yield. Benzylamines were selectively oxidized to oximes, while general primary alkylamines possessing the α-C–H bond gave mixtures of oximes, nitroso dimers, and azoxy compounds.