Diastereoselective Synthesis of Nitropyrrolizidines from Enantiopure exo- 4-Nitro-3,5-diphenylproline through 1,3-Dipolar Cycloadditions of non- Stabilized Azomethine Ylides

Enantiopure exo-4-nitro-3,5-diphenylproline reacts with aldehydes and electrophilic alkenes, in good yields, through a multicomponent 1,3-dipolar cycloaddition where the intermediate azomethine ylide is generated by the decarboxylative route. The reactions with maleimides afford diastereoselectively nitropyrrolizidines. Dimethyl fumarate and 1,2-bis(phenylsulfonyl)ethylene also give variable mixtures of diastereoisomeric nitropyrrolizidines. The replacement of aldehydes by phenyl-3-buten-2- one also affords satisfactory results with high diastereoselection although in lower yields. The stereochemical outcome is studied and defined according to the absolute configuration of the resulting cycloadducts.We gratefully acknowledge financial support from the Spanish Ministerio de Economía y Competitividad (MINECO) (projects CTQ2013-43446-P and CTQ2014-51912-REDC), the Spanish Ministerio de Economía, Industria y Competitividad, Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER, EU) (projects CTQ2016-76782-P and CTQ2016-81797-REDC), the Generalitat Valenciana (PROMETEO2009/039 and PROMETEOII/2014/ 017) and the University of Alicante

Enantioselective 1,3-Dipolar Cycloaddition Using (Z)-α-Amidonitroalkenes as a Key Step to the Access to Chiral cis-3,4-Diaminopyrrolidines

The enantioselective 1,3-dipolar cycloaddition between imino esters and (Z)-nitroalkenes bearing a masked amino group in the β-position was studied using several chiral ligands and silver salts. The optimized reaction conditions were directly applied to the study of the scope of the reaction. The determination of the absolute configuration was evaluated using NMR experiments and electronic circular dichroism (ECD). The reduction and hydrolysis of both groups was performed to generate in an excellent enantiomeric ratio the corresponding cis-2,3-diaminoprolinate.We gratefully acknowledge financial support from the Spanish Ministerio de Ciencia, Innovación y Universidades (project RED2018-102387-T) the Spanish Ministerio de Economía, Industria y Competitividad, Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER, EU) (projects CTQ2016-76782-P, CTQ2016-80375-P, CTQ2017-82935-P and PID2019-107268GB-I00), the Generalitat Valenciana (IDIFEDER/2021/013, CIDEGENT/2020/058 and APOTIP/2020/002), Medalchemy S. L. (Medalchemy-18T) and the University of Alicante (VIGROB-068, UAUSTI21-05)

Diastereoselective deacylative aldol reaction of 3-acetyl-3-fluorooxindoles with aldehydes

The deacetylative aldol reaction of N-methyl-3-acetyl-3-fluoro-2-oxindole is optimized with benzaldehyde and the most appropriate conditions are used for the survey of the scope of this transformation with different aldehydes. The relative configuration of the resulting compounds is also confirmed. The reaction is diastereoselective and affords the syn-stereoisomer in good yields. DFT calculations are used for the explanation of this diastereoselectivity through a traditional chair-like transition state.We gratefully acknowledge financial support from the Spanish Ministerio de Ciencia, Innovación y Universidades (project RED2018-102387-T) the Spanish Ministerio de Economía, Industria y Competitividad, Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER, EU) (projects CTQ2016-76782-P, CTQ2016-80375-P, CTQ2017-82935-P, PID2019-104090RB-100 and PID2019-107268GB-I00), the Generalitat Valenciana (IDIFEDER/2021/013, CIDEGENT/2020/058 and APOTIP/2020/002), Medalchemy S. L. (Medalchemy-18T) and the University of Alicante (VIGROB-068, UAUSTI21-05). P.M. thanks the Regional Government of Aragon (Grupos 17R-34 and a pre-doctoral contract to M.P.) for financial support. The authors thankfully acknowledge the resources from the super-computers "Memento" and “Cierzo”, technical expertise and assistance provided by BIFI-ZCAM (Universidad de Zaragoza, Spain)

Synthesis of highly functionalized 2-(pyrrolidin-1-yl)thiazole frameworks with interesting antibacterial and antimycobacterial activity

A versatile, facile and concise approach to access to highly substituted functionalized 2-(pyrrolidin-1-yl)thiazole ring system is accomplished. The efficient protocol proceeds by the reaction of corresponding racemic or enantiomerically enriched pyrrolidines and readily available benzoylisothiocyanate in acetonitrile followed by sequential reaction of readily available alpha-bromo ketones in acetone. The selectivity and good yield in the desired product is another important advantage of this reaction protocol. In a few cases, the resulting N-benzoylthiourea intermediate cyclizes spontaneously before reacting with the benzophenone component. Finally, a wide study of the biological scope of this new bisheterocyclic molecules is reported.This work is a part of Samet Belveren's ongoing PhD thesis granted by Mersin University (Project no. BAP-SBE TEB(SB) 2017-2-TP3-2564). The authors thank Mersin University (Turkey) and the University of Alicante for support. We also thank the Scientific and Technological Research Council of Turkey (TÜBİTAK), the Spanish Ministerio de Economía y Competitividad (MINECO) (projects CTQ2013-43446-P and CTQ2014-51912-REDC), the Spanish Ministerio de Economía, Industria y Competitividad, Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER, EU) (projects CTQ2016-76782-P, and CTQ2016-81797-REDC), the Generalitat Valenciana (PROMETEOII/2014/017), (Consolider Ingenio 2010, CSD2007-00006) for research financing

Synthesis and Applications of Polifunctionalized Prolinates

La presente tesis doctoral describe la investigación sobre reacciones de cicloadición 1,3-dipolares, concretamente, la síntesis de moléculas que presentan pirrolidinas, pirrolizidinas δ-lactamas y dicetopiperacinas en su estructura. La preparación de estos compuestos se debe, principalmente, a las actividades biológicas que presentan dichas estructuras heterocíclicas. Además, la tesis está constituida por una introducción general y tres capítulos, los cuales describen la síntesis de compuestos N-heterocíclicos de manera diastereoselectiva. La introducción general describe las reacciones de cicloadición 1,3-dipolares, su importancia y sus características. El capítulo 1 describe la síntesis diastereoselectiva de pirrolidinas espirocíclicas catalizada por acetato de plata. El capítulo 2 se basa en el estudio de reacciones multicomponente para la preparación de pirrolizidinas. En concreto, la reacción se lleva a cabo de manera diastereoselectiva y el proceso se rige por 1,2-prototropía en una reacción 1,3-dipolar via descarboxilativa. El capítulo 3 detalla la síntesis secuencial de derivados de exo-3,5-difenil-4-nitroprolinatos de metilo sustituidos mediante una cicloadición 1,3-dipolar enantioselectiva seguido de una adición de tipo Michael diastereoselectiva.The present work has been possible thanks to funding from the Spanish Ministerio de Economía, Industria y Competitividad, Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER, EU) (projects CTQ2016-76782-P, CTQ2016-80375-P, CTQ2017-82935-P and PID2019-107268GB-I00), Generalitat Valenciana (APOTIP/2020/002) and the University of Alicante

Silver‐Catalyzed Diastereoselective Synthesis of Spirocyclic Pyrrolidine‐Lactones by 1,3‐Dipolar Cycloaddition

The preparation of two enantiomerically enriched amino lactones as chiral starting substrates for asymmetric 1,3‐dipolar cycloadditions is described. They act as precursors of the chiral imino lactones, which form in situ the corresponding azomethine ylides. They react with electrophilic alkenes under silver catalysis to afford spirolactone‐pyrrolidines products. The sequential method consisting in one‐pot imine formation → cycloaddition is optimized and compared with the multicomponent process. The scope of the reaction is studied as well as the stereochemical outcomes and the mechanistic details using DFT calculations and X‐ray diffraction analysis.We gratefully acknowledge financial support from the Spanish Ministerio de Economía y Competitividad (MINECO) Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER, EU) (pro-jects CTQ2013-43446-P, CTQ2014-51912-REDC, CTQ2016-76782-P, CTQ2016-81797-REDC and CTQ2016-76155-R), the Generalitat Valenciana (PROMETEOII/2014/017), the University of Alicante. This research was also supported by the Slovak Research and Development Agency under contract VEGA 1/0489/19

Nitroprolinates as Nucleophiles in Michael‐type Additions and Acylations. Synthesis of Enantiomerically Enriched Fused Amino‐pyrrolidino‐[1,2‐a]pyrazinones and ‐diketopiperazines

The enantioselective formation of nitroprolinates followed by diastereoselective Michael‐type addition onto a second unit of the nitro alkene is studied. The reaction occurred in a one pot‐sequential process controlled by the chiral phosphoramidite⋅silver benzoate complex. The origin of the high diastereoselectivity is studied by DFT computational analysis where the crucial effect of the benzoic acid is justified. The employment of this strategy to the preparation of pyrazine‐2‐ones is also surveyed, as well as the preparation of diketopiperazines from enantiomerically enriched exo‐prolinates using conventional N‐acylation‐amination‐cyclization steps.We gratefully acknowledge financial support from the Spanish Ministerio de Economía y Competitividad (MINECO), Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER, EU) (pro-jects CTQ2013-43446-P, CTQ2014-51912-REDC, CTQ2016-76782-P, CTQ2016-81797-REDC and CTQ2016-76155-R), the Generalitat Valenciana (PROMETEOII/2014/017), the University of Alicante