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Article: Aziridination of alkenes and amidation of alkanes by bis(tosylimido)ruthenium(VI) porphyrins. A mechanistic study

TitleAziridination of alkenes and amidation of alkanes by bis(tosylimido)ruthenium(VI) porphyrins. A mechanistic study
Authors
Issue Date1999
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/journals/jacsat/index.html
Citation
Journal Of The American Chemical Society, 1999, v. 121 n. 39, p. 9120-9132 How to Cite?
AbstractBis(tosylimido)ruthenium(VI) porphyrins, [Ru(VI)(Por)(NTs)2] (Por = TPP, TTP, 4-C1-TPP, 4-MeOTPP, OEP), were prepared in 60-74% yields by treatment of [Ru(II)(Por)(CO)(MeOH)] with (N-(p-tolylsulfonyl)- imino)phenyliodinane (PhI=NTS) in dichloromethane. In dichloromethane containing pyrazole, they reacted with alkenes or alkanes to give tosylamidoruthenium(IV) porphyrins, [Ru(IV)(Por)(NHTs)(pz)], in about 75% yields. The reactions of [Ru(VI)(TPP)(NTs)2] and [Ru(VI)(OEP)(NTs)2] with styrene, para-substituted styrenes, norbornene, cyclooctene, and β- methylstyrene afforded the corresponding N-tosylaziridines in 66-85% yields. The aziridination of cis-stilbene and cis-β-methylstyrene by [Ru(VI)(Por)(NTs)2] is nonstereospecific with a partial loss of the alkene stereochemistry. Kinetic studies on the reactions between [Ru(VI)(TPP)(NTs)2] and 16 alkenes (cyclooctene, norbornene, 2,3-dimethyl-2- butene, styrene, para-substituted styrenes, α and β-methylstyrene, and α- and β-deuteriostyrene) gave the second-order rate constants (k2) ranging from (1.60 ± 0.06) x 10-3 to (90 ± 4) x 10-3 dm3 mo1-1 s-1 at 298 K. The slope of the linear plot of log k2 vs E(l/2) for eight representative alkenes was found to be -1.7 V-1. In the case of para-substituted styrenes, linear correlation between log k(R) (k(R) = relative rate) and σ+ gives a ρ+ value as small as -1.1. However, the effect of para substituents on k(R) can be best accounted for by considering both the polar and spin delocalization effect. Measurements on the secondary deuterium isotope effect revealed that only the β-carbon atom of styrene experienced a significant change in its hybridization in reaching the transition state. All these are consistent with rate-determining formation of a carboradical intermediate. The reactions of [Ru(VI)(TPP)(NTs)2] and [Ru(VI-) (OEP)(NTs)2] with adamantane, cyclohexene, ethylbenzene, and cumene resulted in tosylamidation of these hydrocarbons and afforded the corresponding amides in 52-88% yields. For cyclohexane and toluene, the tosylamidation products were formed in poor yields (ca. 10%). Kinetic studies on the reactions between [Ru(VI-) (TPP)(NTs)2] and nine hydrocarbons (cumene, ethylbenzene, cyclohexene, and para-substituted ethylbenzenes) gave the second-order rate constants (k2) in the range of (0.330 ± 0.008) x 10-3 to (16.5 ± 0.3) x 10-3 dm3 mol-1 s-1. These reactions exhibit a large primary deuterium isotope effect, with a k(H)/k(D) ratio of 11 for the tosylamidation of ethylbenzene. In the case of para-substituted ethylbenzenes, both electron-donating and -withdrawing substituents moderately promote the reaction. There is an excellent linear correlation between log k(R) and a related carboradical parameter. On the basis of these observations, a mechanism involving the rate-limiting formation of a carboradical intermediate is postulated.
Persistent Identifierhttp://hdl.handle.net/10722/69893
ISSN
2015 Impact Factor: 13.038
2015 SCImago Journal Rankings: 7.123
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorAu, SMen_HK
dc.contributor.authorHuang, JSen_HK
dc.contributor.authorYu, WYen_HK
dc.contributor.authorFung, WHen_HK
dc.contributor.authorChe, CMen_HK
dc.date.accessioned2010-09-06T06:17:48Z-
dc.date.available2010-09-06T06:17:48Z-
dc.date.issued1999en_HK
dc.identifier.citationJournal Of The American Chemical Society, 1999, v. 121 n. 39, p. 9120-9132en_HK
dc.identifier.issn0002-7863en_HK
dc.identifier.urihttp://hdl.handle.net/10722/69893-
dc.description.abstractBis(tosylimido)ruthenium(VI) porphyrins, [Ru(VI)(Por)(NTs)2] (Por = TPP, TTP, 4-C1-TPP, 4-MeOTPP, OEP), were prepared in 60-74% yields by treatment of [Ru(II)(Por)(CO)(MeOH)] with (N-(p-tolylsulfonyl)- imino)phenyliodinane (PhI=NTS) in dichloromethane. In dichloromethane containing pyrazole, they reacted with alkenes or alkanes to give tosylamidoruthenium(IV) porphyrins, [Ru(IV)(Por)(NHTs)(pz)], in about 75% yields. The reactions of [Ru(VI)(TPP)(NTs)2] and [Ru(VI)(OEP)(NTs)2] with styrene, para-substituted styrenes, norbornene, cyclooctene, and β- methylstyrene afforded the corresponding N-tosylaziridines in 66-85% yields. The aziridination of cis-stilbene and cis-β-methylstyrene by [Ru(VI)(Por)(NTs)2] is nonstereospecific with a partial loss of the alkene stereochemistry. Kinetic studies on the reactions between [Ru(VI)(TPP)(NTs)2] and 16 alkenes (cyclooctene, norbornene, 2,3-dimethyl-2- butene, styrene, para-substituted styrenes, α and β-methylstyrene, and α- and β-deuteriostyrene) gave the second-order rate constants (k2) ranging from (1.60 ± 0.06) x 10-3 to (90 ± 4) x 10-3 dm3 mo1-1 s-1 at 298 K. The slope of the linear plot of log k2 vs E(l/2) for eight representative alkenes was found to be -1.7 V-1. In the case of para-substituted styrenes, linear correlation between log k(R) (k(R) = relative rate) and σ+ gives a ρ+ value as small as -1.1. However, the effect of para substituents on k(R) can be best accounted for by considering both the polar and spin delocalization effect. Measurements on the secondary deuterium isotope effect revealed that only the β-carbon atom of styrene experienced a significant change in its hybridization in reaching the transition state. All these are consistent with rate-determining formation of a carboradical intermediate. The reactions of [Ru(VI)(TPP)(NTs)2] and [Ru(VI-) (OEP)(NTs)2] with adamantane, cyclohexene, ethylbenzene, and cumene resulted in tosylamidation of these hydrocarbons and afforded the corresponding amides in 52-88% yields. For cyclohexane and toluene, the tosylamidation products were formed in poor yields (ca. 10%). Kinetic studies on the reactions between [Ru(VI-) (TPP)(NTs)2] and nine hydrocarbons (cumene, ethylbenzene, cyclohexene, and para-substituted ethylbenzenes) gave the second-order rate constants (k2) in the range of (0.330 ± 0.008) x 10-3 to (16.5 ± 0.3) x 10-3 dm3 mol-1 s-1. These reactions exhibit a large primary deuterium isotope effect, with a k(H)/k(D) ratio of 11 for the tosylamidation of ethylbenzene. In the case of para-substituted ethylbenzenes, both electron-donating and -withdrawing substituents moderately promote the reaction. There is an excellent linear correlation between log k(R) and a related carboradical parameter. On the basis of these observations, a mechanism involving the rate-limiting formation of a carboradical intermediate is postulated.en_HK
dc.languageengen_HK
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/journals/jacsat/index.htmlen_HK
dc.relation.ispartofJournal of the American Chemical Societyen_HK
dc.titleAziridination of alkenes and amidation of alkanes by bis(tosylimido)ruthenium(VI) porphyrins. A mechanistic studyen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0002-7863&volume=121&spage=9120&epage=9132&date=1999&atitle=Aziridination+of+alkenes+and+amidation+of+alkanes+by+bis(tosylimido)ruthenium(VI)+porphyrins.++A+mechanistic+studyen_HK
dc.identifier.emailHuang, JS:jshuang@hkucc.hku.hken_HK
dc.identifier.emailChe, CM:cmche@hku.hken_HK
dc.identifier.authorityHuang, JS=rp00709en_HK
dc.identifier.authorityChe, CM=rp00670en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1021/ja9913481en_HK
dc.identifier.scopuseid_2-s2.0-0032830991en_HK
dc.identifier.hkuros50018en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0032830991&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume121en_HK
dc.identifier.issue39en_HK
dc.identifier.spage9120en_HK
dc.identifier.epage9132en_HK
dc.identifier.isiWOS:000083009700017-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridAu, SM=7005457811en_HK
dc.identifier.scopusauthoridHuang, JS=7407192639en_HK
dc.identifier.scopusauthoridYu, WY=7403913673en_HK
dc.identifier.scopusauthoridFung, WH=7102150303en_HK
dc.identifier.scopusauthoridChe, CM=7102442791en_HK

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