Aktivace vazby uhlík-vodík: Porovnání verzí

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Dalšího pokroku dosáhly nezávisle na sobě dvě skupiny v&nbsp;roce 1982. [[Robert G. Bergman]] popsal přechodným kovem řízenou mezimolekulární aktivaci vazby uhlík-vodík u neaktivovaných a zcela nenasycených ulovodíků pomocí oxidační adice. [[Fotolýza|Fotolýzou]] Cp*Ir(PMe<sub>3</sub>)H<sub>2</sub> (Cp* = [[pentamethylcyklopentadienyl]]) připravil koordinačně nenasycenou sloučeninou Cp*Ir(PMe<sub>3</sub>), která reagovala v&nbsp;oxidační adici s&nbsp;[[cyklohexan]]em a [[neopentan]]em za tvorby příslušných hydridoalkylových komplexů, Cp*Ir(PMe<sub>3</sub>)HR, (R = cyklohexyl či neopentyl).<ref>{{Citace periodika | autor1 = Andrew H. Janowicz | autor2 = Robert G. Bergman | titul = Carbon–hydrogen activation in saturated hydrocarbons: direct observation of M + R−H &rarr; M(R)(H) | periodikum = Journal of the American Chemical Society | rok vydání = 1982 | strany = 352–354 | doi = 10.1021/ja00365a091}}</ref>
 
<!-- W. A. G. Graham found that thezjistil, sameže hydrocarbonsstejné reactuhlovodíky withreagují s&nbsp;Cp*Ir(CO)<sub>2</sub> uponpo irradiationvystavení to afford thesvětlu relatedza alkylhydridovzniku complexesalkylhydridokomplexů Cp*Ir(CO)HR, wherekde R =je cyclohexylcyklohexyl andči neopentyl, respectively.<ref>{{citeCitace journalperiodika | last1 = Hoyano | first1autor1 = James K. | last2 = GrahamHoyano | first2autor2 = William A. G. | year = 1982William | titletitul = Oxidative addition of the carbon–hydrogen bonds of neopentane and cyclohexane to a photochemically generated iridium(I) complex | journalperiodikum = [[J.Journal Am.of Chem.the Soc.]]American |Chemical volumeSociety =| 104rok |vydání issue= =1982 13| pagesstrany = 3723–3725 | doi = 10.1021/ja00377a032 }}</ref> In the latter example, the reaction is presumed to proceed via the oxidative addition of alkane to a 16-electron iridium(I) intermediate, Cp*Ir(CO), formed by irradiation of Cp*Ir(CO)<sub>2</sub>.
 
U této reakce se předpokládá, že probíhá přes oxidační adici alkanu na 16elektronový iridný meziprodukt Cp*Ir(CO), henž se [[fotochemie|fotochemicky]] vytváří z&nbsp;Cp*Ir(CO)<sub>2</sub>.
:[[Soubor:CHactRGB+WAGimproved.png|thumb|center|340px|C–H activation by Bergman et al. (left) and Graham et al.]]
 
:[[Soubor:CHactRGB+WAGimproved.png|thumb|center|340px350px|C–HAktivace activationvazby C–H bypodle BergmanBergmana et al. (leftvlevo) anda GrahamGrahama et al.]]
The selective activation and functionalization of alkane C–H bonds was reported using a [[tungsten]] complex outfitted with [[pentamethylcyclopentadienyl]], [[Metal nitrosyl|nitrosyl]], [[allyl]] and neopentyl ligands, Cp*W(NO)(η<sup>3</sup>-allyl)(CH<sub>2</sub>CMe<sub>3</sub>).<ref>{{cite journal|last=Baillie|first=Rhett A.|author2=Legzdins, Peter|title=Distinctive Activation and Functionalization of Hydrocarbon C–H Bonds Initiated by Cp*W(NO)(η<sup>3</sup>-allyl)(CH<sub>2</sub>CMe<sub>3</sub>) Complexes|journal=Acc. Chem. Res.|year=2013|pages=330–340|doi=10.1021/ar400108p|pmid=24047442|volume=47|issue=2}}</ref>
 
TheByly selectivepopsány activationselektivní andaktivace functionalizationa offunkcionalizace alkanealkanových vazeb C–H bondspomocí was reported using akomplexů [[tungstenwolfram]]u complex outfitted with s&nbsp;[[pentamethylcyclopentadienylpentamethylcyklopentadien]]ylovými, [[Metal nitrosyl|nitrosyl]]ovými, [[allyl]]ovými anda neopentylneopentylovými ligandsligandy, Cp*W(NO)(η<sup>3</sup>-allyl)(CH<sub>2</sub>CMe<sub>3</sub>).<ref>{{citeCitace periodika journal|last=Baillie|first autor1 = Rhett A. Baillie |author2 autor2 =Legzdins, Peter Legzdins |title titul = Distinctive Activation and Functionalization of Hydrocarbon C–H Bonds Initiated by Cp*W(NO)(η<sup>3</sup>-allyl)(CH<sub>2</sub>CMe<sub>3</sub>) Complexes |journal periodikum =Acc. Chem.[[Accounts of Chemical Research]] Res.|year rok vydání = 2013 |pages strany = 330–340 | doi = 10.1021/ar400108p | pmid = 24047442|volume=47|issue=2}}</ref>
:[[Image:PentaneActivation.png|400px|center|C–H activation of pentane, as seen in Ledgzdins et al., ''J. Am. Chem. Soc.'' 2007; 129, 5372–3.]]
 
:[[Soubor:PentaneActivation.png|400px|center|Aktivace vazby C–H u pentanu]]
In one example involving this system, the alkane [[pentane]] is selectively converted to the [[halocarbon]] ''1-iodopentane''. This transformation was achieved via the thermolysis of Cp*W(NO)(η<sup>3</sup>-allyl)(CH<sub>2</sub>CMe<sub>3</sub>) in pentane at [[room temperature]], resulting in elimination of [[neopentane]] by a pseudo-first-order process, generating an undetectable electronically and sterically unsaturated [[electron counting|16-electron]] intermediate that is coordinated by an [[hapticity|η<sup>2</sup>]]-[[butadiene]] ligand. Subsequent intermolecular activation of a pentane solvent molecule then yields an [[electron counting|18-electron]] complex possessing an ''n''-pentyl ligand. In a separate step, reaction with [[iodine]] at −60&nbsp;°C liberates 1-iodopentane from the complex.
 
Jedním z&nbsp;přílkladů využití tohoto postupu je selektivní přeměna [[pentan]]u na [[halogenderiváty|halogenovaný uhlovodík]] ''1-jodpentan''. Provádí se termolýzou Cp*W(NO)(η<sup>3</sup>-allyl)(CH<sub>2</sub>CMe<sub>3</sub>) v&nbsp;pentanu za pokojové teploty, vedoucí k&nbsp;eliminaci [[neopentan]]u v&nbsp;reakci [[řád reakce|reakci pseudoprvního řádu]], přes nedetekovatelný elektronově a stericky nenasycený 16elektronový mezprodukt koordinovaný s&nbsp;[[hapticita|η<sup>2</sup>]]-[[buta-1,3-dien]]ovým ligandem. Následnou mezimolekulární aktivací pentanu (sloužícího jako rozpouštědlo) vzniká 18elektronový komplex obsahující ''n''-pentylový ligand. V&nbsp;jiném kroku reakcí s&nbsp;[[jod]]em při −60&nbsp;°C se z&nbsp;komplexu uvolní 1-jodpentan.
==Directed C-H activation==
 
Directed-, chelation-assisted-, or "guided" C-H activation involves [[directing group]]s that influence regio- and stereochemistry.<ref name="Bruckl">{{cite journal | title = Innate and Guided C-H Functionalization Logic | journal = Accounts of Chemical Research | year = 2012 | volume = 45 | issue = 6 | pages = 826–839 | last1 = Brückl | first1 = T. | last2 = Baxter | first2 = R. D. | last3 = Ishihara | first3 = Y. | last4 = Baran | first4 = P. S. | author-link4 = Phil S. Baran | doi = 10.1021/ar200194b| pmid = 22017496 | pmc = 3288638 }}</ref> This is the most useful style of C-H activation in organic synthesis. [[N,N-dimethylbenzylamine]] undergoes [[cyclometalation]] readily by many transition metals.<ref>{{cite journal | last1 = Chetcuti | first1 = Michael J. | last2 = Ritleng | first2 = Vincent | year = 2007 | title = Formation of a Ruthenium–Arene Complex, Cyclometallation with a Substituted Benzylamine, and Insertion of an Alkyne | journal = J. Chem. Educ. | volume = 84 | issue = 6| page = 1014 | doi=10.1021/ed084p1014| bibcode = 2007JChEd..84.1014C }}</ref> A semi-practical implementations involve weakly coordinating directing groups, as illustrated by the [[Murai reaction]].<ref>{{cite journal|last=Murai|first=Shinji|author2=Kakiuchi, Fumitoshi |author3=Sekine, Shinya |author4=Tanaka, Yasuo |author5=Kamatani, Asayuki |author6=Sonoda, Motohiro |author7= Chatani, Naoto |title=Efficient catalytic addition of aromatic carbon–hydrogen bonds to olefins|journal=Nature|year=1993|volume=366|issue=6455|pages=529–531|doi=10.1038/366529a0|bibcode = 1993Natur.366..529M }}</ref>
== Řízená C-H aktivace ==
<!-- Directed-, chelation-assisted-, or "guided" C-H activation involves [[directing group]]s that influence regio- and stereochemistry.<ref name="Bruckl">{{cite journal | title = Innate and Guided C-H Functionalization Logic | journal = Accounts of Chemical Research | year = 2012 | volume = 45 | issue = 6 | pages = 826–839 | last1 = Brückl | first1 = T. | last2 = Baxter | first2 = R. D. | last3 = Ishihara | first3 = Y. | last4 = Baran | first4 = P. S. | author-link4 = Phil S. Baran | doi = 10.1021/ar200194b| pmid = 22017496 | pmc = 3288638 }}</ref> This is the most useful style of C-H activation in organic synthesis. [[N,N-dimethylbenzylamine]] undergoes [[cyclometalation]] readily by many transition metals.<ref>{{cite journal | last1 = Chetcuti | first1 = Michael J. | last2 = Ritleng | first2 = Vincent | year = 2007 | title = Formation of a Ruthenium–Arene Complex, Cyclometallation with a Substituted Benzylamine, and Insertion of an Alkyne | journal = J. Chem. Educ. | volume = 84 | issue = 6| page = 1014 | doi=10.1021/ed084p1014| bibcode = 2007JChEd..84.1014C }}</ref> A semi-practical implementations involve weakly coordinating directing groups, as illustrated by the [[Murai reaction]].<ref>{{cite journal|last=Murai|first=Shinji|author2=Kakiuchi, Fumitoshi |author3=Sekine, Shinya |author4=Tanaka, Yasuo |author5=Kamatani, Asayuki |author6=Sonoda, Motohiro |author7= Chatani, Naoto |title=Efficient catalytic addition of aromatic carbon–hydrogen bonds to olefins|journal=Nature|year=1993|volume=366|issue=6455|pages=529–531|doi=10.1038/366529a0|bibcode = 1993Natur.366..529M }}</ref>
 
[[File:Figure_1._General_scheme_of_a_Murai_reaction.png|center|thumb|504x504px|Murai reaction. X = [[directing group]].]]