Browsing by Author "Ma, Zhiwei"
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Item Direct and Stereospecific Synthesis of N-H and N-Alkyl Aziridines from Unactivated Olefins Using Hydroxylamine-O-Sulfonic Acids(Wiley, 2017) Ma, Zhiwei; Zhou, Zhe; Kürti, LászlóA RhII-catalyzed direct and stereospecific N-H- and N-alkyl aziridination of olefins is reported that uses hydroxylamine-O-sulfonic acids as inexpensive, readily available, and nitro group-free aminating reagents. Unactivated olefins, featuring a wide range of functional groups, are converted into the corresponding N-H or N-alkyl aziridines in good to excellent yields. This operationally simple, scalable transformation proceeds efficiently at ambient temperature and is tolerant towards oxygen and trace moisture.Item Dirhodium-catalyzed C-H arene amination using hydroxylamines(AAAS, 2016) Paudyal, Mahesh P.; Adebesin, Adeniyi Michael; Burt, Scott R.; Ess, Daniel H.; Ma, Zhiwei; Kürti, László; Falck, John R.Primary and N-alkyl arylamine motifs are key functional groups in pharmaceuticals, agrochemicals, and functional materials, as well as in bioactive natural products. However, there is a dearth of generally applicable methods for the direct replacement of aryl hydrogens with NH2/NH(alkyl) moieties. Here, we present a mild dirhodium-catalyzed C-H amination for conversion of structurally diverse monocyclic and fused aromatics to the corresponding primary and N-alkyl arylamines using NH2/NH(alkyl)-O-(sulfonyl)hydroxylamines as aminating agents; the relatively weak RSO2O-N bond functions as an internal oxidant. The methodology is operationally simple, scalable, and fast at or below ambient temperature, furnishing arylamines in moderate-to-good yields and with good regioselectivity. It can be readily extended to the synthesis of fused N-heterocycles.Item Non-Deprotonative Primary and Secondary Amination of (Hetero)Arylmetals(American Chemical Society, 2017) Zhou, Zhe; Ma, Zhiwei; Behnke, Nicole Erin; Gao, Hongyin; Kürti, László; BioScience Research CollaborativeHerein we disclose a novel method for the facile transfer of primary (−NH2) and secondary amino groups (−NHR) to heteroaryl- as well as arylcuprates at low temperature without the need for precious metal catalysts, ligands, excess reagents, protecting and/or directing groups. This one-pot transformation allows unprecedented functional group tolerance and it is well-suited for the amination of electron-rich, electron-deficient as well as structurally complex (hetero)arylmetals. In some of the cases, only catalytic amounts of a copper(I) salt is required.