- Tandem nucleophilic addition-cycloaddition of arynes with α-iminoesters: Two concurrent pathways to imidazolidines
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The tandem nucleophilic addition-cycloaddition reaction has been developed for the synthesis of functionalized imidazolidine derivatives. A variety of α-iminoesters and aryne precursors were well tolerated under the mild reaction conditions. This asymmetric cycloaddition afforded imidazolidine derivatives with high yields, complete regioselectivities, and excellent diastereo- and enantioselectivities. Aryne-induced ylides working as 1,3-dipoles for asymmetric cycloaddition are the notable feature of the present reaction. In the tandem reaction, the [3+2] cycloaddition of aryne-induced ylides with metallized α-iminoesters and metal-catalyzed [3+2] cycloaddition of azomethine ylide with α-iminoesters are two concurrent pathways to imidazolidines.
- Jia, Hao,Guo, Zhenyan,Liu, Honglei,Mao, Biming,Shi, Xueyan,Guo, Hongchao
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supporting information
p. 7050 - 7053
(2018/07/05)
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- Enantiodivergent Synthesis of Bis-Spiropyrrolidines via Sequential Interrupted and Completed (3 + 2) Cycloadditions
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Both (5R)- and (5S)-1,7-diazaspiro[4.4]nonan-6-ones are obtained via a sequence of interrupted and completed stepwise (3 + 2) cycloadditions between azomethine ylides and π-deficient alkenes. The only source of chirality along the whole process is an enantiopure ferrocenyl pyrrolidine catalytic ligand. When the starting imine incorporates two aryl groups or one aryl group with one electron-releasing substituent, the reaction between the azomethine ylide and the alkene stops at the first step, leading to the corresponding Michael adduct. When imines derived from p-methoxybenzaldehyde are used, the corresponding syn-α-amino-γ-nitro ester is obtained with almost complete enantiocontrol. In contrast, imines derived from benzophenone lead to the corresponding anti analogue. From this interrupted (3 + 2) cycloaddition, cis- and trans-α-amino-γ-lactams can be obtained via hydrogenation of the nitro group followed by in situ cyclization. Imines derived from these latter compounds are the precursors of N-metalated azomethine ylides from which up to four new chiral centers can be generated via completed (3 + 2) cycloaddition reactions with full regio- and diastereocontrol. Cis- and trans-γ-lactams lead to opposite bis-spiropyrrolidine enantiomers. Therefore, both enantiomeric series of spiro compounds can be obtained by means of the same catalytic system. The potential of these rigid, densely substituted homochiral compounds in medicinal chemistry is briefly described.
- Conde, Egoitz,Rivilla, Iván,Larumbe, Amaia,Cossío, Fernando P.
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p. 11755 - 11767
(2015/12/11)
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- Ligand-Controlled Diastereoselective 1,3-Dipolar Cycloadditions of Azomethine Ylides with Methacrylonitrile
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Copper-catalyzed reactions of glycine ester arylimines and methacrylonitrile provide selective access to either the endo or exo pyrrolidine cycloadducts. DFT calculations have elucidated the origins of ligand-controlled diastereoselectivity.
- Walton, Mary C.,Yang, Yun-Fang,Hong, Xin,Houk,Overman, Larry E.
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supporting information
p. 6166 - 6169
(2016/01/09)
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- Cu(I)-Catalyzed Highly Enantioselective [3 + 3] Cycloaddition between Two Different 1,3-Dipoles, Phthalazinium Dicyanomethanides and Iminoester-Derived Azomethine Ylides
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(Chemical Equation Presented). The Cu(I)-catalyzed highly enantioselective [3 + 3] cycloaddition between two different 1,3-dipoles, phthalazinium dicyanomethanides and iminoester-derived azomethine ylides, has been achieved under mild reaction conditions, providing novel chiral heterocyclic compounds, 2,3,4,11b-tetrahydro-1H-pyrazino[2,1-a]phthalazine derivatives, in high yields with excellent diastereo- and enantioselectivies (up to 99% yield, 99% ee, >20:1 dr).
- Yuan, Chunhao,Liu, Honglei,Gao, Zhenzhen,Zhou, Leijie,Feng, Yalin,Xiao, Yumei,Guo, Hongchao
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supporting information
p. 26 - 29
(2015/07/28)
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- Tricyclic analogues of epidithiodioxopiperazine alkaloids with promising in vitro and in vivo antitumor activity
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Epipolythiodioxopiperazine (ETP) alkaloids are structurally elaborate alkaloids that show potent antitumor activity. However, their high toxicity and demonstrated interactions with various biological receptors compromises their therapeutic potential. In an effort to mitigate these disadvantages, a short stereocontrolled construction of tricyclic analogues of epidithiodioxopiperazine alkaloids was developed. Evaluation of a small library of such structures against two invasive cancer cell lines defined initial structure-activity relationships (SAR), which identified 1,4-dioxohexahydro-6H-3,8a-epidithiopyrrolo[1,2-a]pyrazine 3c and related structures as particularly promising antitumor agents. ETP alkaloid analogue 3c exhibits low nanomolar activity against both solid and blood tumors in vitro. In addition, 3c significantly suppresses tumor growth in mouse xenograft models of melanoma and lung cancer, without obvious signs of toxicity, following either intraperitoneal (IP) or oral administration. The short synthesis of molecules in this series will enable future mechanistic and translational studies of these structurally novel and highly promising clinical antitumor candidates.
- Baumann, Marcus,Dieskau, André P.,Loertscher, Brad M.,Walton, Mary C.,Nam, Sangkil,Xie, Jun,Horne, David,Overman, Larry E.
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p. 4451 - 4457
(2015/07/27)
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- Stereospecific synthesis of pyrrolidines with varied configurations via 1,3-dipolar cycloadditions to sugar-derived enones
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Enantiomerically pure pyrrolidines have been obtained by 1,3-dipolar cycloaddition of stabilized azomethine ylides and sugar enones (dihydropyranones) derived from pentoses. Thus, the S-enone (menthyl 3,4-dideoxy-(1S)-pent-3-enopyranosid-2-ulose) was prepared from d-xylose, while the R analogue was obtained from l-arabinose. The dipoles were generated in situ from α-arylimino esters of common amino acids (glycine, alanine, or phenylalanine) and aromatic aldehydes (benzaldehyde, 3-formylpyridine and 4-methoxybenzaldehyde). Under optimized conditions, the cycloaddition reactions were highly diastereo- and regioselective to yield, in most of the cases, a very major adduct of the 16 theoretically possible. The diastereoselectivity relies on the strict stereocontrol exerted by the stereogenic center of the pyranone. Thus, the (S)-enone, derived from d-xylose, gave tetrasubstituted pyrrolidines having a defined stereochemistry for the four stereocenters of the ring, while they had the opposite configuration when starting from the (R)-dihydropyranone. Furthermore, some endo-cycloadducts underwent isomerization of the carbons vicinal to the nitrogen atom to afford pyrrolidines with a rather unusual stereochemistry for the direct dipolar cycloadditions.
- Udry, Guillermo A. Oliveira,Repetto, Evangelina,Varela, Oscar
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p. 4992 - 5006
(2014/06/23)
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- Search of antimycobacterial activities in hybrid molecules with benzopyran skeleton
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A series of hybrid molecules (7-9, 12, 13, and 14-18) consisting of chromans and pyrolidines or cyclic amines were prepared either by (3 + 2) cycloaddition of nitrostyrenes and azomethine ylide or by three component reactions of chromanyl aldehydes, acetylenes, and cyclic amines. All the synthesized compounds were evaluated against both avirulent (H37Ra) and virulent (H37Rv) strains of Mycobacterium tuberculosis. Out of all the compounds screened, compounds 16, 17, and 18 were found to be active against the virulent strain M. tubercolosis H37Rv displaying MIC in the range of 6.25-1.56 μg/ml against. Springer Science+Business Media, LLC 2010.
- Tripathi, Rama P.,Bisht, Surendra Singh,Pandey, Vivek Parashar,Pandey, Sarvesh K.,Singh, Shubhra,Sinha, Sudhir Kumar,Chaturvedi, Vinita
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experimental part
p. 1515 - 1522
(2012/06/15)
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- PhIO as a powerful cyclizing reagent: Regiospeciflc [3+2]-tandem oxidative cyclization of imine toward cofacially self-aggregated low molecular mass organic materials
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The powerful cyclization and tandem oxidation property of environmentally benign PhIO is developed for the first time, which leads to regiospecific [3+2]-tandem oxidative cyclization of imine at room temperature in rapid access to a new class of compounds
- Pandit, Palash,Chatteijee, Nirbhik,Halder, Samiran,Hota, Sandip K.,Patra, Amarendra,Maiti, Dilip K.
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supporting information; experimental part
p. 2581 - 2584
(2009/07/25)
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- PROCESS FOR PRODUCTION OF MONO-SUBSTITUTED ALKYLATED COMPOUND USING ALDIMINE OR DERIVATIVE THEREOF
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Disclosed is a process for producing an asymmetric mono-substituted alkylated compound of an α-amino acid which is represented by a specific formula by using an aldimine-type Schiff base. In the process, the alkylation of an aldimine-type Schiff base in a medium in the presence of an optically active quaternary ammonium salt phase transfer catalyst and an inorganic base is started, and subsequently the reaction is quenched at any time preceding the completion of the stoichimetrical reaction, thereby yielding a mono-substituted alkylated product having a high optical purity.
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Page/Page column 87-88
(2008/06/13)
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- Aziridines as templates: A general strategy for the stereospecific synthesis of 2-azetidinones
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Various routes to a variety of azridine-2-carboxylates have been described and the stereochemistry of these compounds has been determined by spectroscopic methods. Further, greater diversity of β-lactams via ring expansion of these azridines-2-carboxylates were obtained by a general, efficient and direct stereospecific approach.
- Sharma,Kanwar, Seema,Rajpoot, Shivani
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- Process for preparing xanthine phosphodiesterase V inhibitors and precursors thereof
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A process for preparing xanthine phosphodiesterase V inhibitors, and compounds utilized in said process. The process includes a five-step methodology for efficient synthesis of Compound 5 without intermediate purifications or separations, a dihalogenation step to synthesize Compound 7, and a coupling reaction to produce Compound 9.
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