159870-91-4Relevant articles and documents
Catalytic Enantioselective Synthesis of Heterocyclic Vicinal Fluoroamines by Using Asymmetric Protonation: Method Development and Mechanistic Study
Ashford, Matthew W.,Xu, Chao,Molloy, John J.,Carpenter-Warren, Cameron,Slawin, Alexandra M. Z.,Leach, Andrew G.,Watson, Allan J. B.
, p. 12249 - 12255 (2020)
A catalytic enantioselective synthesis of heterocyclic vicinal fluoroamines is reported. A chiral Br?nsted acid promotes aza-Michael addition to fluoroalkenyl heterocycles to give a prochiral enamine intermediate that undergoes asymmetric protonation upon rearomatization. The reaction accommodates a range of azaheterocycles and nucleophiles, generating the C?F stereocentre in high enantioselectivity, and is also amenable to stereogenic C?CF3 bonds. Extensive DFT calculations provided evidence for stereocontrolled proton transfer from catalyst to substrate as the rate-determining step, and showed the importance of steric interactions from the catalyst's alkyl groups in enforcing the high enantioselectivity. Crystal structure data show the dominance of noncovalent interactions in the core structure conformation, enabling modulation of the conformational landscape. Ramachandran-type analysis of conformer distribution and Protein Data Bank mining indicated that benzylic fluorination by this approach has the potential to improve the potency of several marketed drugs.
Regioselective bromination of fused heterocyclic N-oxides
Wengryniuk, Sarah E.,Weickgenannt, Andreas,Reiher, Christopher,Strotman, Neil A.,Chen, Ke,Eastgate, Martin D.,Baran, Phil S.
supporting information, p. 792 - 795 (2013/04/10)
A mild method for the regioselective C2-bromination of fused azine N-oxides is presented, employing tosic anhydride as the activator and tetra-n-butylammonium bromide as the nucleophilic bromide source. The C2-brominated compounds are produced in moderate to excellent yields and with excellent regioselectivity in most cases. The potential extension of this method to other halogens, effecting C2-chlorination with Ts2O/TBACl is also presented. Finally, this method could be incorporated into a viable one-pot oxidation/bromination process, using methyltrioxorhenium/urea hydropgen peroxide as the oxidant.
