Umpolung reactions of imines, especially the asymmetric reactions, have been extensively studied as they provide access to important chiral amines in an efficient manner. The reactions studied range from simple Michael reactions to several kinds of other reactions such as the aza-benzoin reaction, aza-Stetter reaction, addition with MBH carbonate, and Ir-catalysed allylation. Herein, we report the
Tandem <i>N</i>,<i>N</i>-Dialkylation Reaction of <i>N</i>-Trimethylsilyl α-Iminoesters Utilizing an Umpolung Reaction and Characteristics of the Silyl Substituent: Synthesis of Pyrrolidine, Piperidine, and Iminodiacetate
with organometallics gave directly N-alkylaminoesters in high yields without the need for removing a protecting group at the nitrogen atom. Efficient syntheses of pyrrolidines, piperidines, and iminodiacetate derivatives were also developed via tandem N,N- or N,C-dialkylation reactions utilizing characteristics of the silyl substituent. Furthermore, under the influence of silica gel, the addition of
A highlyenantioselectiveFriedel–Craftsalkylation reaction of indoles with acyclic α-substituted β-nitroacrylates is developed under the catalysis of Ni(ClO4)2–bisoxazoline complex at 1 mol % catalyst loading, affording chiral indolic β-nitroesters bearing all-carbon quaternary stereocenters in excellent yields and ees of up to 97%. Transformation of one of the products to β2,2-amino ester and t
Ir/PTC cooperatively catalyzed asymmetric umpolung allylation of α-imino ester enabled synthesis of α-quaternary amino acid derivatives bearing two vicinal stereocenters
作者:Yong-Liang Su、Yu-Hui Li、Yu-Gen Chen、Zhi-Yong Han
DOI:10.1039/c6cc09654a
日期:——
A novel Ir/PTC cooperatively catalyzed asymmetric umpolung addition of simple [small alpha]-imino esters is developed and it provides facile access to [small alpha]-quaternary amino acidderivatives bearing two vicinal stereocenters. Both the...
Chemo- and Enantioselective Brønsted Acid-Catalyzed Reduction of α-Imino Esters with Catecholborane
作者:Dieter Enders、Andreas Rembiak、Bianca Anne Stöckel
DOI:10.1002/adsc.201300352
日期:2013.7.8
The chemo‐ and enantioselectivereduction of α‐imino esters with catecholborane has been developed employing 10 mol% of an enantiopure BINOL‐based phosphoric acid as organocatalyst. Various differently substituted aromatic α‐amino acid derivatives can be achieved in almost quantitative yields and very good to excellent enantioselectivities of up to 96% ee under mild reaction conditions.