Réactions de cycloadditions stéréosélectives originales reposant sur l'utilisation de vinylcyclopropanes électro-appauvris et la catalyse au palladium(0)

This manuscript presents the development of novel palladium-catalysed [3+2] cycloaddition reactions between vinylcyclopropanes and various dipolarophiles. The first part of this work focused on the dearomatization of nitroaromatic compounds such as 3-nitroindoles and 2-nitrobenzofurans through a cycloaddition process with vinylcyclopropanes. In a second time, an enantioselective [3+2] cycloaddition of vinylcyclopropanes with α,β-unsaturated aldehydes under a synergistic metal-organocatalytic activation manifold was developed, leading to highly substituted cyclopentane scaffolds with very high enantioselectivity. In a third part of this work, the extension of this methodology towards the synthesis of heterocyclic compounds was investigated. A first approach dealing with the in situ generation of nitrogen-containing 1,3- and 1,4-dipoles did not lead to the desired reactivity, which prompted us to develop a palladium(0)-catalysed cycloaddition of vinylcyclopropanes and electron-deficient imines to synthesize pyrrolidine derivatives.Ce manuscrit présente le développement de nouvelles réactions de cycloaddition [3+2] palladocatalysées entre des vinylcyclopropanes électro-appauvris et diverses espèces dipolarophiles. La première partie de ces travaux a porté sur la désaromatisation de composés nitroaromatiques tels que les 3-nitroindoles ou les 2-nitrobenzofuranes par le biais d'un procédé de cycloaddition impliquant les vinylcyclopropanes. Une seconde méthodologie de cycloaddition [3+2] énantiosélective entre des aldéhydes ?,?-insaturés et des vinylcyclopropanes a été développée. En tirant parti du concept de catalyse synergique métallo-organique, divers cyclopentanes hautement fonctionnalisés ont été obtenus, avec notamment des énantiosélectivités très élevées. Dans une troisième partie de ces travaux, l'extension de cette méthodologie à la synthèse de composés hétérocycliques a été étudiée ; une première approche impliquant la formation in situ de dipôles-1,3 et -1,4 azotés n'ayant pas abouti à la réactivité désirée, nous avons alors développé une méthodologie de cycloaddition de vinylcyclopropanes et d'imines électro-déficientes par catalyse au palladium(0) menant à des dérivés de pyrrolidine

Original stereoselective cycloaddition reactions based on the use of electron-poor vinylcyclopropanes and palladium(0) calaysis

Ce manuscrit présente le développement de nouvelles réactions de cycloaddition [3+2] palladocatalysées entre des vinylcyclopropanes électro-appauvris et diverses espèces dipolarophiles. La première partie de ces travaux a porté sur la désaromatisation de composés nitroaromatiques tels que les 3-nitroindoles ou les 2-nitrobenzofuranes par le biais d'un procédé de cycloaddition impliquant les vinylcyclopropanes. Une seconde méthodologie de cycloaddition [3+2] énantiosélective entre des aldéhydes ?,?-insaturés et des vinylcyclopropanes a été développée. En tirant parti du concept de catalyse synergique métallo-organique, divers cyclopentanes hautement fonctionnalisés ont été obtenus, avec notamment des énantiosélectivités très élevées. Dans une troisième partie de ces travaux, l'extension de cette méthodologie à la synthèse de composés hétérocycliques a été étudiée ; une première approche impliquant la formation in situ de dipôles-1,3 et -1,4 azotés n'ayant pas abouti à la réactivité désirée, nous avons alors développé une méthodologie de cycloaddition de vinylcyclopropanes et d'imines électro-déficientes par catalyse au palladium(0) menant à des dérivés de pyrrolidine.This manuscript presents the development of novel palladium-catalysed [3+2] cycloaddition reactions between vinylcyclopropanes and various dipolarophiles. The first part of this work focused on the dearomatization of nitroaromatic compounds such as 3-nitroindoles and 2-nitrobenzofurans through a cycloaddition process with vinylcyclopropanes. In a second time, an enantioselective [3+2] cycloaddition of vinylcyclopropanes with α,β-unsaturated aldehydes under a synergistic metal-organocatalytic activation manifold was developed, leading to highly substituted cyclopentane scaffolds with very high enantioselectivity. In a third part of this work, the extension of this methodology towards the synthesis of heterocyclic compounds was investigated. A first approach dealing with the in situ generation of nitrogen-containing 1,3- and 1,4-dipoles did not lead to the desired reactivity, which prompted us to develop a palladium(0)-catalysed cycloaddition of vinylcyclopropanes and electron-deficient imines to synthesize pyrrolidine derivatives

Cyclostationarity Detectors for Cognitive Radio: Architectural Tradeoffs

Cyclostationarity detectors have been studied in the past few years as an efficient means for signal detection under low-SNR conditions. On the other hand, some knowledge about the signal is needed at the detector. This is typically the case in Cognitive Radio spectrum secondary usage, where the primary system is known. This paper focuses on two hardware architectures of cyclostationarity detectors for OFDM signals. The first architecture aims at secondary ISM band use, considering IEEE802.11a/g as the primary system. In this scenario, low latency is required. The second architecture targets TV band secondary usage, where DVB-T signals must be detected at very low SNR. The paper focuses on the architectural tradeoffs that the designer has to face, and how his/her choices will influence either performance or complexity. Hardware complexity evaluation on FPGA is provided for detectors that have been tested in the laboratory under real conditions.</p

Copper(I)-Catalyzed Dearomative (3+2) Cycloaddition of 3-Nitroindoles with Propargylic Nucleophiles: a Straightforward Entry for The Preparation of Cyclopenta[b]indolines

The copper(I)-catalyzed dearomatization of 3-nitroindoles with propargylic nucleophiles is described. In mild reaction conditions, this original dearomative (3+2) cycloaddition process gives access to a wide variety of cyclopenta[b]indolines in good to excellent yields, with high functional group tolerance. Furthermore, an enantioselective version of this reaction is reachable by employing chiral phosphorous ligands. A mechanism proposal is given, based on kinetic studies

Palladium(0)-Catalyzed Dearomatization of 2-Nitrobenzofurans through Formal (3+2) Cycloadditions with Vinylcyclopropanes: A Straightforward Access to Cyclopenta[b]benzofurans

International audienc

FPGA Implementation of a Wideband Multi-Gb/s 5G BF-OFDM Transceiver

International audienceThis paper describes a Field Programmable Gate Array (FPGA) implementation of a multi-Gb/s Block Filtered (BF) OFDM transceiver, fully 5G NR compatible. The main obstacles for such a work are (i) the support of multiple configurations and parameters, (ii) the high bandwidth w.r.t the board clock frequency and (iii) the intrinsic complexity of BF-OFDM. We prove that despite these barriers an hardware implementation of this waveform is possible, even with a bandwidth up to 400 MHz. We based our developments on the following pillars: smart layout of the basic modules, parallelization of dedicated functions design and ad hoc architecture. Measurements and complexity analysis demonstrate the high flexibility of BF-OFDM

An MC-SS Platform for Short-Range Communications in the Personal Network Context

Abstract Wireless personal area networks (WPANs) have gained interest in the last few years, and several air interfaces have been proposed to cover WPAN applications. A multicarrier spread spectrum (MC-SS) air interface specified to achieve 130&#8201;Mbps in typical WPAN channels is presented in this paper. It operates in the 5.2&#8201;GHz ISM band and achieves a spectral efficiency of 3.25&#8201; . Besides the robustness of the MC-SS approach, this air interface yields to reasonable implementation complexity. This paper focuses on the hardware design and prototype of this MC-SS air interface. The prototype includes RF, baseband, and IEEE802.15.3 compliant medium access control (MAC) features. Implementation aspects are carefully analyzed for each part of the prototype, and key hardware design issues and solutions are presented. Hardware complexity and implementation loss are compared to theoretical expectations, as well as flexibility is discussed. Measurement results are provided for a real condition of operations.</p

An MC-SS platform for short-range communications in the Personal Network context

Wireless Personal Area Networks (WPAN) has gained interest in the last few years and several air interfaces have been proposed to cover WPAN applications. A Multi-Carrier Spread Spectrum (MC-SS) air interface specified to achieve 130 Mbps in typical WPAN channels, is presented in this paper. It operates in the 5.2 GHz ISM band and achieves a spectral efficiency of 3.25 b.s-1.Hz-1. Besides the robustness of the MC-SS approach, this air interface yields to reasonable implementation complexity. This paper focuses on the hardware design and prototype of this MC-SS air interface. The prototype includes RF, baseband and IEEE802.15.3 compliant Medium Access Control (MAC) features. Implementation aspects are carefully analyzed for each part of the prototype and key hardware design issues and solutions are presented. Hardware complexity and implementation loss are compared to theoretical expectation, as well as flexibility are discussed. Measurement results are provided for real condition of operations