Fragmentation of Nitrone Triflates to 9-Membered Rings
摘要:
A new fragmentative rearrangement of nitrone derivatives to form 9-membered rings is reported. The fragmentations are triggered when nitrones are treated with triflic anhydride; a C-C bond antiperiplanar to the cleaving N-O bond is activated either by an oxygen lone pair or by an electron-rich aromatic ring. In the former case, further cyclization of the 9-membered intermediate leads to a rearranged condensed ring system, but when triggered by arenes, 9-membered ring amides are isolated.
Fragmentation of Nitrone Triflates to 9-Membered Rings
摘要:
A new fragmentative rearrangement of nitrone derivatives to form 9-membered rings is reported. The fragmentations are triggered when nitrones are treated with triflic anhydride; a C-C bond antiperiplanar to the cleaving N-O bond is activated either by an oxygen lone pair or by an electron-rich aromatic ring. In the former case, further cyclization of the 9-membered intermediate leads to a rearranged condensed ring system, but when triggered by arenes, 9-membered ring amides are isolated.
Oxidation of silyl enolates was found to be smoothly catalyzed by [Cu(bpy)(BF4)2(H2O)2(bpy)]n (bpy = 4,4′-bipyridine) under molecular oxygen, and provided the corresponding α-hydroxy carbonyl compounds in high yield. The insoluble organic–inorganic hybrid polymer was readily recovered by centrifugation after the completion of reaction, and the recovered catalyst could be reused.
strategy for the encapsulation of magneticnanobeads was developed by using the in situ self-assembly of an organic-inorganichybrid polymer. The hybrid polymer of [Cu(bpy)(BF(4))(2)(H(2)O)(2)](bpy)}(n) (bpy=4,4'-bipyridine) was constructed on the surface of amino-functionalized magnetic beads and the resulting hybrid-polymer-encapsulated beads were utilized as catalysts for the oxidation of silyl enolates
were synthesized with high enantiopurity by asymmetric decarboxylative chlorination and subsequent nucleophilicsubstitution. We recently reported the asymmetric decarboxylative chlorination of β-ketocarboxylic acids in the presence of a chiral primary amine catalyst to obtain α-chloroketones with high enantiopurity. Here, we found that nucleophilicsubstitution of the resulting α-chloroketones with tetrabutylammonium
Lewis base-catalyzed [2,3]-Wittig rearrangement of silyl enolates generated from α-allyloxy carbonyl compounds is described. The [2,3]-Wittig rearrangement of silyl enolates generated from α-allylo...
Silyl enolates generated from α-allyloxy ketones afforded the [2,3]-Wittig rearrangement products in good to high yields in the presence of a catalytic amount of Lewis base such as lithium 2-pyrrol...