The triazene moiety as a protecting group for aromatic amines
摘要:
Reaction of (2-,(3-, and (4-bromophenyl)-3,3-(1,4-butanediyl)triazenes (derived from the corresponding 2-, 3-, and 4-bromoanilines) with sec- or tert-butyllithiums gave the corresponding (triazenylaryl)-lithiums; these intermediates reacted with a variety of electrophiles to give substituted aryl triazenes. These products cound be converted to substituted anilines by reduction or to novel substituted aromatics by a modified Sandmeyer reaction.
Chiral Phosphoric Acid Catalyzed Kinetic Resolution of 2‐Amido Benzyl Alcohols: Asymmetric Synthesis of 4
<i>H</i>
‐3,1‐Benzoxazines
作者:Subramani Rajkumar、Mengyao Tang、Xiaoyu Yang
DOI:10.1002/anie.201913896
日期:2020.2.3
An efficient method for the asymmetricsynthesis of 4H-3,1-benzoxazines was developed by kinetic resolution of 2-amido benzyl alcohols using chiral phosphoric acidcatalyzed intramolecular cyclizations. A broad range of benzyl alcohols (both secondary and tertiaryalcohols) were kinetically resolved with high selectivities, with an s factor of up to 94. Mechanistic studies were performed to elucidate
late-stage [11C], [13C] and [14C]carbon isotope labeling of cyclic carbamates is reported. This protocol allows the incorporation of carbon dioxide, the primary source of carbon-14 and carbon-11 radioisotopes, in a direct, cost-effective and sustainable manner. A disconnection/reconnection strategy, involving ringopening/isotopic closure, was also implemented.
Beyond a Protecting Reagent: DMAP-Catalyzed Cyclization of Boc-Anhydride with 2-Alkenylanilines
作者:Ya-Nan Huang、Yin-Long Li、Jian Li、Jun Deng
DOI:10.1021/acs.joc.6b00519
日期:2016.6.3
quinolines from 2-alkenylanilines has been described; the reaction involves an unexpected DMAP-catalyzed cyclization of 2-alkenylanilines with di-tert-butyl dicarbonate (Boc2O, 2.0 equiv), and a series of tert-butyl quinolin-2-yl carbonate with various functional groups have been synthesized in good yields under mild conditions. Furthermore, the tert-butyl quinolin-2-yl carbonate can be easily converted into
Intramolecular Addition of Triarylmethanes to Alkynes Promoted by KO<i>t</i>Bu/DMF: A Synthetic Approach to Indene Derivatives
作者:Yan-yan Chen、Zhen-yu Chen、Niu-niu Zhang、Jia-hua Chen、Xue-jing Zhang、Ming Yan
DOI:10.1002/ejoc.201501356
日期:2016.1
been developed. The reaction was efficiently promoted by KOtBu/DMF without any transition-metal catalyst. A variety of indene derivatives were prepared in moderate to good yields. A cascade cyclization of 2-alkyl-substituted substrates at elevated reaction temperature gave bicyclic indene derivatives. The reaction is proposed to proceed through the generation of a triphenylmethyl radical.
Borane-Catalyzed Synthesis of Quinolines Bearing Tetrasubstituted Stereocenters by Hydride Abstraction-Induced Electrocyclization
作者:Alexander F. G. Maier、Sebastian Tussing、Hui Zhu、Garrit Wicker、Pavleta Tzvetkova、Ulrich Flörke、Constantin G. Daniliuc、Stefan Grimme、Jan Paradies
DOI:10.1002/chem.201804777
日期:2018.11.2
stereocenters from vinyl anilines has been developed. Mechanistic studies and quantum‐mechanical investigations support the hydride abstraction/electrocyclization/hydride addition mechanism. The products were obtained in up to 99 % yield with a diastereoselectivity of >99 % in favour for the 3a‐5‐cis isomer.