Microwave-Assisted Ring-Closing Metathesis Revisited. On the Question of the Nonthermal Microwave Effect

Garbacia, Stefania; Desai, Bimbisar; Lavastre, Olivier; Kappe, C. Oliver

doi:10.1021/jo035135c

Cited by 125 publications

(64 citation statements)

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“…This technique, first introduced by Ley et al in 2001 (see Section 2.9.4), [51] is becoming increasingly popular, as demonstrated by the many recently published examples. [52][53][54][55][56][57][58][59][60] Systematic studies on temperature profiles and the thermal stability of ionic liquids under microwave irradiation conditions by Leadbeater and Torenius [52,53] have shown that addition of a small amount of an ionic liquid (0.1 mmol mL À1 solvent) suffices to obtain dramatic changes in the heating profiles by changing the overall dielectric properties (namely, tand) of the reaction medium.…”

Section: Heck Reactionsmentioning

confidence: 99%

“…With microwaves, otherwise sluggish RCM protocols have been reported to be completed within minutes or even seconds. [49,55,71,[125][126][127][128] In 2003, for example, Efskind and Undheim reported the domino RCM of dienyne 14 with a Grubbs type II catalyst (Scheme 16). [127] While the thermal process (toluene, 85 8C) required multiple addition of fresh catalyst (3 10 mol %) over a period of 9 h to furnish a 92 % yield of product 15, microwave irradiation for 10 min at 160 8C (5 mol % catalyst, toluene) led to full conversion.…”

Section: Other Transition-metal-mediated Processesmentioning

confidence: 99%

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Controlled Microwave Heating in Modern Organic Synthesis

2004

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Although fire is now rarely used in synthetic chemistry, it was not until Robert Bunsen invented the burner in 1855 that the energy from this heat source could be applied to a reaction vessel in a focused manner. The Bunsen burner was later superseded by the isomantle, oil bath, or hot plate as a source for applying heat to a chemical reaction. In the past few years, heating and driving chemical reactions by microwave energy has been an increasingly popular theme in the scientific community. This nonclassical heating technique is slowly moving from a laboratory curiosity to an established technique that is heavily used in both academia and industry. The efficiency of “microwave flash heating” in dramatically reducing reaction times (from days and hours to minutes and seconds) is just one of the many advantages. This Review highlights recent applications of controlled microwave heating in modern organic synthesis, and discusses some of the underlying phenomena and issues involved.

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Section: Heck Reactionsmentioning

confidence: 99%

Section: Other Transition-metal-mediated Processesmentioning

confidence: 99%

Controlled Microwave Heating in Modern Organic Synthesis

2004

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“…Os resultados mostram que as reações se completam em minutos, e até poucos segundos, no lugar de horas à temperatura ambiente 32 . Danishefsky et.…”

Section: Figura 2 Catalisadores Do Tipo Metal-carbenounclassified

A reação de metátese de olefinas: reorganização e ciclização de compostos orgânicos

Frederico¹,

Brocksom²,

Brocksom³

2005

Quím. Nova

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Recebido em 12/7/04; aceito em 13/10/04; publicado na web em 4/2/05 THE OLEFIN METATHESIS REACTION: REORGANIZATION AND CICLIZATION OF ORGANIC COMPOUNDS. The olefin metathesis reaction allows the exchange of complex alkyl units between two olefins, with the formation of a new olefinic link and a sub-product olefin usually ethylene. This reaction has found extensive application in the last ten years with the development of the Grubbs and Schrock catalysts, in total synthesis of complex organic molecules, as opposed to the very important use in the petrochemical industry with relatively simple molecules. This review intends to trace a historical and mechanistic pathway from industry to academy, before illustrating the more recent advances.Keywords: olefin metathesis; ring-closing metathesis; cross metathesis. No sentido químico, a palavra metátese descreve, por tradução direta do grego "troca de posição", a troca de ligações covalentes entre dois alcenos (ou olefinas) ou entre um alceno e um alcino. Na química de olefinas, ela se refere a uma redistribuição do esqueleto carbônico (Esquema 1), no qual ligações duplas carbono-carbono são rearranjadas na presença de um complexo metal-carbeno, representando um método catalítico de quebra e de formação de ligações múltiplas carbono-carbono. Esta reação é conhecida na petroquímica e na química dos polímeros há mais de 40 anos 1 , mas só na década de noventa, com o advento de novos e eficientes catalisadores, desenvolvidos principalmente pelos grupos de pesquisa de Schrock 2,3 e Grubbs 4,5 , ela emergiu como uma potente ferramenta na química orgânica acadêmica. INTRODUÇÃOEstes novos catalisadores proporcionaram um grande aumento no número de aplicações desta reação, atraindo a atenção de quí-micos acadêmicos e industriais. Atualmente, estas aplicações estão relacionadas com a metátese entre dois alcenos (metátese de dienos) ou entre um alceno e um alcino (metátese de eninos) mostradas no Esquema 2.A reação entre duas olefinas distintas recebe o nome de metátese cruzada (CM do inglês "cross-metathesis") e a sua versão intramolecular, a reação entre duas ligações duplas na mesma molécula, é conhecida como metátese de fechamento de anel (RCM; "ring-closing metathesis"). A formação de dienos não conjugados a partir de olefinas cíclicas é conhecida por abertura de anel por metátese (ROM; "ring-opening metathesis") e, formalmente é a reação inversa da RCM. Reações de polimerização podem ocorrer entre dienos acíclicos (ADMET; "acyclic diene metathesis polymerization") ou ainda com alcenos cíclicos, através do processo de abertura de anel por metátese (ROMP; "ring-opening metathesis polymerization"). As combinações dos processos de CM, RCM e ROM deram origem a uma nova e eficiente estratégia para

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“…However the results that are presented are often extremely specific and can not be applied to other conditions. The mechanisms that have been proposed to explain the warming through microwaves do not seem to sustain the "microwave effect" affirmation, indeed, there are results where such effect is not observed (Roy et al, 2000), then this issue is controversial (Garbacia et al, 2003;Wittaker, 2005;Hoogenboom et al, 2005) and deserves more study. Polymers (Popescu et al, 2008), metals (Roy et al, 1999) and ceramic (Xiang et al, 2005) have been heated up with microwaves.…”

Section: Introductionmentioning

confidence: 99%

Thermal Microwave Processing of Materials

Aguilar-Garib¹

2011

Advances in Induction and Microwave Heating of Mineral and Organic Materials

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Microwave-Assisted Ring-Closing Metathesis Revisited. On the Question of the Nonthermal Microwave Effect

Cited by 125 publications

References 20 publications

Controlled Microwave Heating in Modern Organic Synthesis

Controlled Microwave Heating in Modern Organic Synthesis

A reação de metátese de olefinas: reorganização e ciclização de compostos orgânicos

Thermal Microwave Processing of Materials

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