Enantioselective Synthesis of 2-Substituted Pyrrolidines via Intramolecular Reductive Amination
Catalyzed by the complex generated in situ from iridium and the chiral ferrocene ligand, tert -butyl (4-oxo-4-arylbutyl)carbamate substrates were deprotected and then reductively cyclised to form 2-substituted arylpyrrolidines in a one-pot manner, in which the intramolecular reductive amination was the key step. A range of chiral 2-substituted arylpyrrolidines were synthesised in up to 98percent yield and 92percent ee.
Direct α-C-H bond functionalization of unprotected cyclic amines
Cyclic amines are ubiquitous core structures of bioactive natural products and pharmaceutical drugs. Although the site-selective abstraction of C-H bonds is an attractive strategy for preparing valuable functionalized amines from their readily available parent heterocycles, this approach has largely been limited to substrates that require protection of the amine nitrogen atom. In addition, most methods rely on transition metals and are incompatible with the presence of amine N-H bonds. Here we introduce a protecting-group-free approach for the α-functionalization of cyclic secondary amines. An operationally simple one-pot procedure generates products via a process that involves intermolecular hydride transfer to generate an imine intermediate that is subsequently captured by a nucleophile, such as an alkyl or aryl lithium compound. Reactions are regioselective and stereospecific and enable the rapid preparation of bioactive amines, as exemplified by the facile synthesis of anabasine and (-)-solenopsin A.
Chen, Weijie,Ma, Longle,Paul, Anirudra,Seidel, Daniel
p. 165 - 169
(2018/02/06)
Hammett correlation of nornicotine analogues in the aqueous aldol reaction: Implications for green organocatalysis
(Chemical Equation Presented) A series of meta- and para-substituted 2-arylpyrrolidines were synthesized and examined for their ability to catalyze an aqueous aldol reaction under buffered conditions. Kinetic analysis of arylpyrrolidine-catalyzed reactions displayed a linear Hammett correlation with ρ = 1.14 (R2 = 0.996), indicating that the reaction is accelerated by electron-withdrawing aryl rings. These results show promise for the development of a synthetically viable aqueous organocatalyst.
Rogers, Claude J.,Dickerson, Tobin J.,Brogan, Andrew P.,Janda, Kim D.
p. 3705 - 3708
(2007/10/03)
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