70665-05-3Relevant academic research and scientific papers
Rapid Synthesis of α-Chiral Piperidines via a Highly Diastereoselective Continuous Flow Protocol
Shan, Chao,Xu, Jinping,Cao, Liming,Liang, Chaoming,Cheng, Ruihua,Yao, Xiantong,Sun, Maolin,Ye, Jinxing
, p. 3205 - 3210 (2022/05/07)
A practical continuous flow protocol has been developed using readily accessible N-(tert-butylsulfinyl)-bromoimine and Grignard reagents, providing various functionalized piperidines (34 examples) in superior results (typically >80% yield and with >90:10 dr) within minutes. The high-performance scale-up is smoothly carried out, and efficient synthesis of the drug precursor further showcases its utility. This flow process offers rapid and scalable access to enantioenriched α-substituted piperidines.
Enantioselective Synthesis of 2-Substituted Pyrrolidines via Intramolecular Reductive Amination
Chang, Mingxin,Guo, Haodong,Huang, Haizhou,Zhang, Tao,Zhao, Wenlei,Zhou, Huan
, p. 2713 - 2719 (2019/06/19)
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.
Chemoenzymatic Synthesis of Substituted Azepanes by Sequential Biocatalytic Reduction and Organolithium-Mediated Rearrangement
Zawodny, Wojciech,Montgomery, Sarah L.,Marshall, James R.,Finnigan, James D.,Turner, Nicholas J.,Clayden, Jonathan
supporting information, p. 17872 - 17877 (2019/01/04)
Enantioenriched 2-aryl azepanes and 2-arylbenzazepines were generated biocatalytically by asymmetric reductive amination using imine reductases or by deracemization using monoamine oxidases. The amines were converted to the corresponding N′-aryl ureas, which rearranged on treatment with base with stereospecific transfer of the aryl substituent to the 2-position of the heterocycle via a configurationally stable benzyllithium intermediate. The products are previously inaccessible enantioenriched 2,2-disubstituted azepanes and benzazepines.
Synthesis of chiral cyclic amines via Ir-catalyzed enantioselective hydrogenation of cyclic imines
Zhang, Ying,Kong, Duanyang,Wang, Rui,Hou, Guohua
, p. 3006 - 3012 (2017/04/11)
A highly enantioselective hydrogenation of cyclic imines for synthesis of chiral cyclic amines has been realized. With the complex of iridium and (R,R)-f-spiroPhos as the catalyst, a range of cyclic 2-aryl imines were smoothly hydrogenated under mild conditions without any additive to provide the corresponding chiral cyclic amines with excellent enantioselectivities of up to 98% ee. Moreover, this method could be successfully applied to the synthesis of (+)-(6S,10bR)-McN-4612-Z.
Simultaneous engineering of an enzyme's entrance tunnel and active site: The case of monoamine oxidase MAO-N
Li, Guangyue,Yao, Peiyuan,Gong, Rui,Li, Jinlong,Liu, Pi,Lonsdale, Richard,Wu, Qiaqing,Lin, Jianping,Zhu, Dunming,Reetz, Manfred T.
, p. 4093 - 4099 (2017/07/10)
A new directed evolution approach is presented to enhance the activity of an enzyme and to manipulate stereoselectivity by focusing iterative saturation mutagenesis (ISM) simultaneously on residues lining the entrance tunnel and the binding pocket. This combined mutagenesis strategy was applied successfully to the monoamine oxidase from Aspergillus Niger (MAO-N) in the reaction of sterically demanding substrates which are of interest in the synthesis of chiral pharmaceuticals based on the benzo-piperidine scaffold. Reversal of enantioselectivity of Turner-type deracemization was achieved in the synthesis of (S)-1,2,3,4-tetrahydro-1-methyl-isoquinoline, (S)-1,2,3,4-tetrahydro-1-ethylisoquinoline and (S)-1,2,3,4-tetrahydro-1-isopropylisoquinoline. Extensive molecular dynamics simulations indicate that the altered catalytic profile is due to increased hydrophobicity of the entrance tunnel acting in concert with the altered shape of the binding pocket.
Enantioselective Direct Synthesis of Free Cyclic Amines via Intramolecular Reductive Amination
Zhang, Ying,Yan, Qiaozhi,Zi, Guofu,Hou, Guohua
supporting information, p. 4215 - 4218 (2017/08/23)
Chiral cyclic amines can be prepared via intramolecular reductive amination of N-Boc-protected amino ketones in a one-pot process. With the complex of iridium and f-spiroPhos as the catalyst, a range of N-Boc-protected amino ketones are smoothly transformed into chiral cyclic free amines in high yields and excellent enantioselectivities (up to 97% ee). Moreover, this method can also be successfully applied to the synthesis of a κ-opioid receptor selective antagonist, (S)-1.
Determination of the Absolute Configuration of Cyclic Amines with Bode's Chiral Hydroxamic Esters Using the Competing Enantioselective Conversion Method
Burtea, Alexander,Rychnovsky, Scott D.
, p. 4195 - 4198 (2017/08/23)
The competing enantioselective conversion (CEC) strategy has been extended to cyclic amines. The basis for the CEC approach is the use of two complementary, enantioselective reactions to determine the configuration of the enantiopure substrate. Bode's chiral acylated hydroxamic acids are very effective enantioselective acylating agents for a variety of amines. Pseudoenantiomers of these acyl-transfer reagents were prepared and demonstrated to react with enantiopure cyclic amines with modest to high selectivity. The products were analyzed by ESI-MS to determine selectivity, and the results were used to assign the configuration of the amine substrate. The method was applicable to a variety of cyclic amines as well as primary amines and acyclic secondary amines. The method is limited to amines that are unhindered enough to react with the reagents, and not all amine substitution patters lead to high selectivity.
Enzyme Cascades in Whole Cells for the Synthesis of Chiral Cyclic Amines
Hepworth, Lorna J.,France, Scott P.,Hussain, Shahed,Both, Peter,Turner, Nicholas J.,Flitsch, Sabine L.
, p. 2920 - 2925 (2017/05/31)
The increasing diversity of reactions mediated by biocatalysts has led to development of multistep in vitro enzyme cascades, taking advantage of generally compatible reaction conditions. The construction of pathways within single whole cell systems is much less explored, yet has many advantages. Herein we report the generation of a successful whole cell de novo enzyme cascade for the diastereoselective and/or enantioselective conversion of simple, linear keto acids into valuable cyclic amine products. The pathway starts with carboxylic acid reduction that triggers a transamination, imine formation, and subsequent imine reduction. Construction and optimization of the system was achieved by standard genetic manipulation and the cascade required only starting material, amine donor, and whole cell catalyst with cofactors provided internally by glucose metabolism. A panel of synthetic keto acids provided access to piperidines in high conversions (up to 93%) and enantiomeric excess (up to 93%).
Stereoselectivity and Structural Characterization of an Imine Reductase (IRED) from Amycolatopsis orientalis
Aleku, Godwin A.,Man, Henry,France, Scott P.,Leipold, Friedemann,Hussain, Shahed,Toca-Gonzalez, Laura,Marchington, Rebecca,Hart, Sam,Turkenburg, Johan P.,Grogan, Gideon,Turner, Nicholas J.
, p. 3880 - 3889 (2016/07/06)
The imine reductase AoIRED from Amycolatopsis orientalis (Uniprot R4SNK4) catalyzes the NADPH-dependent reduction of a wide range of prochiral imines and iminium ions, predominantly with (S)-selectivity and with ee's of up to >99%. AoIRED displays up to 100-fold greater catalytic efficiency for 2-methyl-1-pyrroline (2MPN) compared to other IREDs, such as the enzyme from Streptomyces sp. GF3546, which also exhibits (S)-selectivity, and thus, AoIRED is an interesting candidate for preparative synthesis. AoIRED exhibits unusual catalytic properties, with inversion of stereoselectivity observed between structurally similar substrates, and also, in the case of 1-methyl-3,4-dihydroisoquinoline, for the same substrate, dependent on the age of the enzyme after purification. The structure of AoIRED has been determined in an "open" apo-form, revealing a canonical dimeric IRED fold in which the active site is formed between the N- and C-terminal domains of participating monomers. Co-crystallization with NADPH gave a "closed" form in complex with the cofactor, in which a relative closure of domains, and associated loop movements, has resulted in a much smaller active site. A ternary complex was also obtained by cocrystallization with NADPH and 1-methyl-1,2,3,4-tetrahydroisoquinoline [(MTQ], and it reveals a binding site for the (R)-amine product, which places the chiral carbon within 4 ? of the putative location of the C4 atom of NADPH that delivers hydride to the C? -N bond of the substrate. The ternary complex has permitted structure-informed mutation of the active site, resulting in mutants including Y179A, Y179F, and N241A, of altered activity and stereoselectivity.
One-Pot Cascade Synthesis of Mono- and Disubstituted Piperidines and Pyrrolidines using Carboxylic Acid Reductase (CAR), ω-Transaminase (ω-TA), and Imine Reductase (IRED) Biocatalysts
France, Scott P.,Hussain, Shahed,Hill, Andrew M.,Hepworth, Lorna J.,Howard, Roger M.,Mulholland, Keith R.,Flitsch, Sabine L.,Turner, Nicholas J.
, p. 3753 - 3759 (2016/07/06)
Access to enantiomerically pure chiral mono- and disubstituted piperidines and pyrrolidines has been achieved using a biocatalytic cascade involving carboxylic acid reductase (CAR), ω-transaminase (ω-TA), and imine reductase (IRED) enzymes. Starting from keto acids or keto aldehydes, substituted piperidine or pyrrolidine frameworks can be generated in high conversion, ee, and de in one pot, with each biocatalyst exhibiting chemo-, regio-, and/or stereoselectivity during catalysis. The study also includes a systematic investigation of the effect of the position of a methyl group ring substituent on the IRED-catalyzed reduction of a chiral imine. Analysis of the selectivity observed in these reactions revealed an interesting balance between substrate versus enzyme control; the configurations of the products obtained were rationalized on the basis of minimizing 1,3- or 1,2-steric interactions with incoming NADPH.
