Synthesis of homo and block copolymers of norbornene with W(CO)6 via photo-initiation
TL;DR: In this paper, block copolymers of norbornene and phenylacetylene have been synthesized employing W(CO)6/CCl4 /hν system indicating formation of a metallacarbene as the active species.
About: This article is published in Tetrahedron Letters.The article was published on 1993-09-17. It has received 23 citations till now. The article focuses on the topics: Norbornene & Phenylacetylene.
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440 citations
TL;DR: Since this initial report, various metal vinylidenes and allenylidenes, which are key activation intermediates, have proved extremely useful for many alkyne transformations and contributed to the rational design of new catalytic reactions.
Abstract: The involvement of a catalytic metal vinylidene species was proposed for the first time in 1986 to explain the regioselective formation of vinyl carbamates directly from terminal alkynes, carbon dioxide, and amines. Since this initial report, various metal vinylidenes and allenylidenes, which are key activation intermediates, have proved extremely useful for many alkyne transformations. They have contributed to the rational design of new catalytic reactions. This 20th anniversary is a suitable occasion to present the advancement of organometallic vinylidenes and allenylidenes in catalysis.
410 citations
TL;DR: This Review outlines the general concept of light-gated catalysis based on photocaged and also photoswitchable systems, and discusses relevant examples of the past and recent literature.
Abstract: Having control over an entity or even an entire process is arguably the ultimate demonstration of its understanding and it will enable its potential to be fully exploited. With this in mind, chemists have not only been creating and optimizing a myriad of different catalysts for most (relevant) chemical reactions over the past decades, but have recently started to implement controlling elements into the catalyst design. These incorporated gates operate upon exposure to suitable control stimuli, and light represents perhaps the scientifically and technologically most attractive stimulus. In principle, irradiation can thereby induce activity and selectivity in a given catalyst system with high spatial and temporal control, leading to an overall localization and amplification of an optical signal and translation into chemical action. While nature has developed and utilized this concept, in particular in the processes of vision and photomovement, such artificial photocontrolled catalyst systems offer unique opportunities and have high potential for future applications. In this Review, we outline the general concept of light-gated catalysis based on photocaged and also photoswitchable systems, and discuss relevant examples of the past and recent literature.
298 citations
112 citations
TL;DR: In this paper, the authors discuss the problem of bestrahlung in a katalytischen system, i.e., kontrolle uber einen Gegenstand oder einen gesamten Prozess, ist zweifelsohne der ultimative Beweis fur dessen Verstandnis.
Abstract: Kontrolle uber einen Gegenstand oder einen gesamten Prozess auszuuben, ist zweifelsohne der ultimative Beweis fur dessen Verstandnis und ermoglicht erst die vollstandige Nutzung seines Potenzials. Vor diesem Hintergrund haben Chemiker in den vergangenen Jahrzehnten fur die meisten (relevanten) chemischen Reaktionen nicht nur eine Vielzahl von Katalysatoren entwickelt und optimiert, sondern vor kurzem auch damit begonnen, Steuerungselemente in das Katalysatordesign einzufuhren. Diese integrierten Kontrolleinheiten werden durch Einwirkung geeigneter Stimuli reguliert, wobei Licht aus wissenschaftlicher und technologischer Sicht vermutlich am attraktivsten ist. Bestrahlung kann hierbei prinzipiell sowohl Aktivitat als auch Selektivitat in einem gegebenen katalytischen System mit hoher raumlicher und zeitlicher Prazision steuern, die zu einer allgemeinen Lokalisierung und Verstarkung des optischen Signals und dessen Umwandlung in chemische Aktivitat fuhrt. Wahrend in der Natur dieses Konzept bereits erfolgreich Anwendung findet, im Speziellen beim Sehprozess und bei der Photobewegung, eroffnen derartige kunstliche lichtgesteuerte katalytische Systeme einzigartige Moglichkeiten und verfugen uber ein hohes Potenzial fur zukunftige Anwendungen. In diesem Aufsatz beschreiben wir die grundsatzliche Idee der lichtgesteuerten Katalyse basierend auf photoaktivierbaren und photoschaltbaren Systemen und diskutieren relevante Beispiele aus der alteren und neueren Literatur.
93 citations
References
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TL;DR: In this paper, a mechanism for the formation of these compounds is outlined, and the mechanism for their formation is described in terms of the insertion of metalladichlorocarbene moieties into the carbon double bond.
35 citations
TL;DR: In this paper, the role and some characteristic properties of the precipitate formed upon irradiation of the W(CO) 6 /CCl 4 catalyst system in the photoinduced methathesis of 2-pentene were described.
18 citations