Key ionic intermediates of the Heck reaction of arene diazonium salts have been intercepted and structurally characterized by ESI‐MS/MS. The use of electrospray ionization enables the ionic species to be transferred smoothly to the gas phase. A catalytic cycle for this reaction involving all the Pd cationic species intercepted has been proposed (see scheme).

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The "dba-free" Heck-Matsuda reaction was investigated via direct ESI-MS(/MS) monitoring. Palladium species involved in the reduction of Pd(II) during a Wacker type reaction and several "dba-free" arylpalladium transient complexes were detected and characterized. Based on these findings, a more comprehensible catalytic cycle for this pivotal reaction is suggested.

Ionische Schlüsselintermediate in der Heck‐Reaktion von Arendiazoniumsalzen wurden mit ESI‐MS/MS abgefangen und strukturell charakterisiert. Durch Elektrospray‐Ionisation können die ionischen Spezies zerstörungsfrei in die Gasphase überführt werden. Ein Katalysezyklus wird vorgeschlagen, der alle in der Reaktion abgefangenen kationischen Pd‐Spezies umfasst (siehe Schema).

Abstract:The implementation of chemical reactions in continuous mode under microfluidic conditions by the use of microreactors is a very attractive alternative to the traditional batch and semi-batch mode currently used for chemical synthesis. The fine control of the stoichiometry, kinetics and thermal exchange of the reaction, as well as the easy scale up, low physical space demand for installation/operation and the easy implementation of in-line analysis techniques for in process controls approach the laboratory development to a reproducible, robust, safe, cost-competitive and environmentally sustainable chemical process. ResumoA execução de reações químicas em modo contínuo de operação sob condições microfluídicas em micro reatores é uma alternativa muito atraente às condições em batelada e semi batelada tradicionalmente empregadas para a síntese química. O fino controle da estequiometria, cinética e troca térmica da reação em execução, bem como a facilidade na ampliação de escala de produção, baixa demanda por espaço físico para sua instalação/operação e viabilidade na implementação de técnicas de análise em linha para os controles em processo, aproximam o desenvolvimento laboratorial da implementação de um processo químico reprodutível, robusto, seguro, de custo competitivo e ambientalmente sustentável.Palavras-chave: Micro reatores; processos químicos; química em fluxo.

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SummaryThe enantioselective carbenoid insertion into C(sp3)–H bonds is an important tool for the synthesis of complex molecules due to the high control of enantioselectivity in the formation of stereogenic centers. This paper presents a brief review of the early issues, related mechanistic studies and recent applications on this chemistry area.

The essential oil from Rosmarinus officinalis presents antifungal activity and is used in industry as a natural preserving agent. However, essential oils are unstable compounds.