Silver(I) triflate-catalyzed protocol for the post-ugi synthesis of spiroindolines

A silver(I) triflate-catalyzed protocol for the post-Ugi synthesis of tetracyclic spiroindolines has been developed. The protocol worked best for indole-3-carbaldehyde-derived Ugi adducts obtained using anilines and 3-aryl propiolic acids. Thus, it is complementary to the previous cationic gold-catalyzed procedure that was developed for analogues Ugi substrates derived from aliphatic amines and 3-alkyl propiolic acids. Furthermore, we have demonstrated that under our new settings this domino Friedel-Crafts ipso cyclization / imine trapping process could be efficiently combined with the preceding four-component Ugi reaction into a two-step one-pot transformation

(PVDF)2(PEO)2 miktoarm star copolymers: Synthesis and isothermal crystallization leading to exclusive β-phase formation

In this work, we study how chain topology can induce different polymorphic behaviors in poly(vinylidene fluoride) (PVDF)-based materials. A linear PVDF precursor with two azido groups at the junction point, (PVDFx-N3)2 and three 4-miktoarm star copolymers (PVDFx)2-b-(PEOy)2 with two poly(ethylene oxide) (PEO) and two PVDF arms were synthesized and employed in this study. The amphiphilic miktoarm copolymers were prepared by a combination of anionic ring-opening polymerization, iodine transfer radical polymerization (ITP), and copper-catalyzed azide-alkyne cycloaddition (CuAAC). They have practically similar overall molar mass but different compositions, ideal for performing bulk morphology and crystallization investigations. The isothermal overall crystallization kinetics of the PVDF and PEO arms of the 4-miktoarm star copolymers and representative PEO and PVDF precursors was determined by Differential Scanning Calorimetry (DSC). The results indicate that the star arms crystallized faster than the equivalent precursors as the kinetics are dominated by nucleation effects. The phases formed by the PVDF components in the materials examined were analyzed by studying their melting behavior by DSC, their superstructural morphology by Polarized Light Optical Microscopy (PLOM), and the phase structure by Fourier Transform Infrared Spectroscopy (FTIR). The linear PVDF and (PVDF29-N3)2, exhibited α, β and γ-phases (with a majority of β-phase formation) during melting after isothermal crystallization. The ratio of the different phases depends on the crystallization temperature. An analysis of the multiple melting behavior indicated that the sample forms both α and β-phases initially, and the α-phase partially transforms into the γ-phase during isothermal crystallization when the temperature of crystallization increases. We found a remarkable behavior for the 4-miktoarm star copolymers, as the PVDF arms only form the ferroelectric β-phase when all three materials were isothermally crystallized regardless of the crystallization temperature employed. The presence of the polymorphism in the PVDF was detected by DSC, PLOM, and FTIR. Hence, we have shown that tailoring chain topology in PVDF copolymers can lead to exclusive β-phase formation, a path that can be exploited for future piezoelectric applications.We acknowledge funding from MICINN through grant PID2020-113045GB-C21. We would also like to acknowledge the support of the Basque Government through grant IT1503-22. N. M. thankfully acknowledges his Ph.D. fellowship from the POLYMAT Basque Center for Macromolecular Design and Engineering. J. M. acknowledges partial financial support from the IBERDROLA Foundation. Y.P., G.P., A.P., V.R., and N.H. thankfully acknowledge the support of King Abdullah University of Science and Technology (KAUST)

Synthesis and post-transformations of propiolic acid-derived Ugi adducts

The research described in this thesis centers on the application of 3-substituted propiolic acids in a four-component Ugi reaction. The triple bond of propiolic acid in combination with other functionalities produces an important type of Ugi adducts which could be then readily applied in a large variety of post transformations providing a diversity-oriented access towards a large number of heterocyclic scaffolds. Chapter 1 serves as an introduction into the post-Ugi chemistry in general, and into the reactivity of Ugi-adducts bearing C-C triple bond in particular. The objectives and targets of the current research are also formulated in this chapter. Chapter 2 is dedicated to the elaboration of a novel cascade transformation involving Ugi reaction followed by enolization-triggered 5-endo-dig carbocyclization and retro-Claisen fragmentation providing an efficient and fast access to 1H-pyrrol-2(5H)-one core. Chapter 3 describes a comprehensive study on gold- and silver-catalyzed cyclisomerizations of hydroxypropargylamides into oxazepines. Three different types of hydroxypropargylamide substrates derived from either amide coupling or Ugi reaction have been validated providing selective and general access to a medium-ring oxazepine core. Chapter 4 deals with a two-step sequence involving Ugi reaction followed by reductive Heck cyclization leading to a 3-benzazepine framework. Several aspects related to the substrate scope and the optimal distribution of the required functional groups have been addressed, resulting in a diversity-oriented synthesis of a small library of title compounds, featuring four distinct types of substitution pattern.status: publishe

Diversification of the 3-Benzazepine Scaffold Applying Ugi/Reductive Heck Sequence

© 2015 Elsevier Ltd. All rights reserved. A two step sequence involving Ugi reaction followed by reductive Heck cyclization has been evaluated in order to provide access to a 3-benzazepine framework in a diversity-oriented fashion. Several aspects related to the substrate scope and the optimal distribution of the required functional groups have been addressed, resulting in the construction of a small library of the title compounds, featuring four distinct types of substitution pattern.status: publishe

The Application of Multicomponent Ugi and Passerini Reactions for the One-Pot Synthesis of Pyrrolones and Butenolides

A new protocol for the one-pot synthesis of pyrrolones and butenolides involving an isocyanide-based multicomponent reaction (Ugi or Passerini) followed by a triethylamine-promoted cycloisomerization is described.status: publishe

Assembly of a 1H-Pyrrol-2(5H)-one Core through a Cascade Ugi Reaction/5-endo-dig Carbocyclization/Retro-Claisen Fragmentation Process

A cascade transformation involving the Ugi reaction followed by 5-endo-dig carbocyclization and retro-Claisen fragmentation providing access to a 1H-pyrrol-2(5H)-one core is described. The operating protocol is very similar to the typical Ugi reaction settings, while the overall outcome results from the application of a 3-substituted propiolic acid and a phenylglyoxal as acid and aldehyde components, respectively. The utility of process is demonstrated through the synthesis of a small library of 5-oxo-2,5-dihydro-1H-pyrrole-2-carboxamides.status: publishe

A domino Ugi/Michael approach for the synthesis of alpha,beta-unsaturated gamma-lactams

© 2016 Elsevier Ltd. All rights reserved. A domino Ugi/Michael access to α,β-unsaturated γ-lactams has been elaborated. This protocol offers a simplistic assembly of a α,β-unsaturated γ-lactams in good yields starting from nitrogen-containing heterocyclic aldehydes, amines, 2-alkynoic acids, and isocyanides.status: publishe

Synthesis of thiazolidine-2-thiones through a one-pot A³-coupling-carbon disulfide incorporation process

A copper-catalyzed two-step one-pot procedure for the synthesis of thiazolidine-2-thiones has been developed. The process involves a three-component coupling of an alkyne, an aldehyde, and an amine (A(3)-coupling) followed by trapping the resulting propargylamine with carbon disulfide and subsequent cyclization

Post-Ugi carbocyclization/fragmentation sequence for the synthesis of 6,7-dihydro-5H-pyrrolo[3,4-b]pyridin-5-ones

A two-step one-pot sequence, involving Ugi reaction followed by base-promoted carbocyclization accompanied by cleavage of the isocyanide-originated amide moiety, has been successfully elaborated in order to provide a fast access to 6,7-dihydro-5H-pyrrolo[3,4-b]pyridin-5-ones. When the cyclizations were run under air atmosphere a subsequent oxidation occurred producing oxidized 7-hydroxy-6,7-dihydro-5H-pyrrolo[3,4-b]pyridin-5-ones.status: publishe