- O2-Mediated Oxidation of Aminoboranes through 1,2-N Migration
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In analogy to the classical reaction of C?B bonds with peroxides, the first oxidative functionalization of aminoboranes through a 1,2-N migration was realized. Readily available aliphatic nitro compounds are thereby transformed into N- and O-functionalized hydroxylamines in a single synthetic operation. Addition of hazardous peroxides is avoided. Instead, the insertion of O2, as the terminal oxidant, into Zn?C bonds provides the necessary peroxides. The required zinc organyls, in turn, are formed through a boron-to-zinc exchange, from an organoboronic ester byproduct of the nitro-to-aminoborane transformation.
- Rauser, Marian,Warzecha, Daniel P.,Niggemann, Meike
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supporting information
p. 5903 - 5907
(2018/05/14)
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- Direct Reductive N-Functionalization of Aliphatic Nitro Compounds
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The first general protocol for the direct reductive N-functionalization of aliphatic nitro compounds is presented. The nitro group is partially reduced to a nitrenoid, with a mild and readily available combination of B2pin2 and zinc organyls. Thereby, the formation of an unstable nitroso intermediate is avoided, which has so far severely limited reductive transformations of aliphatic nitro compounds. The reaction is concluded by an electrophilic amination of zinc organyls.
- Rauser, Marian,Ascheberg, Christoph,Niggemann, Meike
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supporting information
p. 3970 - 3974
(2018/02/26)
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- Electrophilic Amination with Nitroarenes
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An exceptionally general electrophilic amination, which directly transforms commercially available nitroarenes into alkylated aromatic aminoboranes with zinc organyl compounds was developed. The reaction starts with a two-step partial reduction of the nitro group to a nitrenoid, which is used in situ as the electrophilic amination reagent. To facilitate isolation, the resulting air- and moisture-sensitive aminoboranes were reacted with a range of electrophiles. The method not only represents a direct transformation of nitro compounds into electrophilic amination reagents but also provides an elegant alternative to dehydrocoupling methods for the generation of aminoboranes.
- Rauser, Marian,Ascheberg, Christoph,Niggemann, Meike
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supporting information
p. 11570 - 11574
(2017/09/11)
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- Catalytic use of zinc amide for transmetalation with allylboronates: General and efficient catalytic allylation of carbonyl compounds, imines, and hydrazones
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The efficient catalytic allylation of ketones, imines, and hydrazones with allylboronates using a catalytic amount of zinc amide is reported. In this reaction, the boron-to-zinc exchange process occurred smoothly to afford the corresponding allylzinc amides, and the desired allylation reactions proceeded in high efficiency (~0.1mol%). A mechanistic study revealed that transmetalation was a rate-determining step in the catalytic cycle, and also that the amide ligand on the zinc center played a key role in preparing reactive allylzinc species. Catalytic asymmetric allylations were also investigated, and high enantioselectivities were obtained using chiral diamine ligands. Copyright
- Cui, Yi,Li, Wei,Sato, Takehiro,Yamashita, Yasuhiro,Kobayashi, Shu
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supporting information
p. 1193 - 1205
(2013/06/04)
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- Facile preparation of allylzinc species from allylboronates and zinc amide via a boron-to-zinc exchange process and their reactions with carbonyl compounds, imines and hydrazones
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Facile formation of allylzinc species from allylboronate and zinc amide was discovered. The boron-to-zinc exchange process occurred smoothly to afford the corresponding allylzinc amides, which were successfully employed in catalytic allylation reactions with electrophiles. Asymmetric catalysis using a chiral zinc amide is also reported.
- Cui, Yi,Yamashita, Yasuhiro,Kobayashi, Shu
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supporting information
p. 10319 - 10321
(2012/11/07)
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- BIS(ALK-2-ENYL)ZINK AUS ORGANOMAGNESIUMHALOGENIDEN
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The dialk-2-enyl zinc compounds II, XI-XIV can be prepared via reaction of ZnCl2 with the corresponding alk-2-enylmagnesium halides I, VII-X at 20-35 deg C in ether in 68-94percent yield.Diprop-2-enylzinc (II) oligomerizes into 2-allylpropane-1,3-diylzinc (III) during attempted sublimation at 30-50 deg C.The yield of II decreases therefore to 15percent.The oligomerization can be prevented by complexation of II with dioxane.In this case II is obtained in 86percent yield by cleavage of the dioxane complex.
- Lehmkuhl, Herbert,Doering, Ingo,McLane, Raymond,Nehl, H.
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