The photo-oxidation of ethene and propene using zinc oxide and titanium oxide-based catalysts has been investigated at various reaction temperatures. The activity of the zinc oxide catalyst (0.25 g) was greatly enhanced when the reaction temperature was raised to 450–500 K, to afford 21 µmol h–1 of ethanal, 16 µmol h–1 of propenal and 49 µmol h–1 of carbon oxides, together with small amounts of propanal and methanal at 493 K. Loading of Group 5 or 6 metal oxide species on zinc oxide suppressed the formation of carbon oxides and propenal, whereas a significant formation of propanal was observed in addition to ethanal. Molybdenum oxide-loaded catalysts showed high selectivities toward oxygen-containing chemicals. Since the MoO3/SiO2 catalyst showed a similar product distribution in the photo-oxidation of propene, surface active centres including molybdenum species on zinc oxide surface seem to be responsible for the reaction. The use of titanium oxide-based catalysts at ambient temperature generally resulted in low selectivities toward oxygen-containing chemicals.
The reaction of alkylphenylacetyl chlorides with aroyl chlorides catalysed by tetrakis(triphenylphosphine)palladium gives α,β-unsaturated ketones selectively via a decarbonylative cross condensation reaction.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReactions of 2-alkoxyfurans with nonacarbonyldiiron or dodecacarbonyltriruthenium giving binuclear vinylcarbene complexes and a 2-pyrone complex. A novel precursor for .alpha.,.beta.-unsaturated alkylidene ligands and an unusual carbonylation of the furansTakeaki Mitsudo, Yasukazu Ogino, Yukiatsu Komiya, Hiroyoshi Watanabe, and Yoshihisa WatanabeCite this: Organometallics 1983, 2, 9, 1202–1207Publication Date (Print):September 1, 1983Publication History Published online1 May 2002Published inissue 1 September 1983https://pubs.acs.org/doi/10.1021/om50003a022https://doi.org/10.1021/om50003a022research-articleACS PublicationsRequest reuse permissionsArticle Views90Altmetric-Citations15LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Reactions of a zerovalent ruthenium complex, Ru(η4-cod)(η6-cot) (3; cod = 1,5-cyclooctadiene, cot = 1,3,5-cyclooctatriene), with maleic anhydride or maleimides under mild reaction conditions afforded a series of novel divalent ruthenacycles 4 with an η5-cyclooctadienyl moiety via oxidative cyclization between the carbon−carbon double bonds of cot and the electron-deficient alkene. The solid-state structure clearly showed a newly constructed ruthenacycle skeleton, which was formed in a trans manner. Complex 4 was further reacted with H2 and HCl to give hydrogenated and protonated succinimides with a C8-ring, respectively. When 4 was heated in toluene, a [6 + 2] cycloadduct of cot and a maleimide was obtained via reductive elimination, which shows that a ruthenium-mediated stepwise [6 + 2] cycloaddition was achieved. The addition of PPh3 to complex 4d promoted the reductive elimination, while bidentate phosphines such as 1,2-bis(diphenylphosphino)ethane did not give the cycloadduct and stable ruthenacycles 11 were formed instead. Reactions of 4 with CO gave novel tricarbonyl ruthenacycles 12 along with dissociation of the cod ligand, where neither reductive elimination nor CO insertion took place. The results of a theoretical study were consistent with the idea that the energy barriers for reductive elimination from ruthenacycles bearing cod or monophosphine ligands were lower than those from a ruthenacycle bearing a diphosphine ligand. The formation of 12 was found to be more energetically favorable than reductive elimination.
Abstract A trifluoromethyl-substituted π-vinylcarbeneiron complex reacts with [KB(sec-Bu)3H] or phenyllithium to afford difluorinated trimethylenemethane iron complexes. This is the first example of the conversion of a π-vinylcarbeneiron complex to a trimethylenemethane complex.
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Abstract The chemistry of η3-vinylcarbene transition-metal complexes is reviewed. The η3-vinylcarbene complexes are prepared by 1) the alkylation of (η3-acryloyl)tricarbonylferrate, 2) the treatment of cyclopropenes with [Fe2(CO)9], 3) the insertion of acetylenes into a carbene–metal double bond, 4) the reaction of acetylene with [ReCl3(Me5C5)]2, 5) the reaction of carbyne complexes with allyl bromides, and 6) the thermal decarbonylation of (η1-vinylcarbene)pentacarbonylchromium. The structures of the complexes, which were determined by X-ray analyses, are represented by the hybrid of the resonance structures (A) and (B). The contribution of the two structures was very sensitive to the respective MLn fragments. The vinylcarbene complex, [Fe(η3-vinylcarbene)(CO)3] (1), is a parent complex of a series of various complexes. The carbene carbons of the reported Fischer-type η3-vinylcarbene complexes are electrophilic. Carbonylation of the η3-vinylcarbene complexes gives η4-vinylketene complexes. Treatment of the η3-vinylcarbene(carbonyl)irons with an excess of tertiary phosphines or bidentate amines gives ferracyclopentenones. Reaction of 1 with isocyanides gives the first example of the η4-vinylketenimine complex. Treatment of 1 with diazomethane gives (η4-1,3-butadiene)tricarbonyliron. The complex 1 with a methoxycarbonyl group on the 3-position reacts with carbon monoxide to give a η4-pyrone complex, which thermally rearranges to its isomer. The rearrangement was deduced to proceed via a η4-methoxyfuran complex. The complex 1 reacts with hydride to give a η3-allyl complex. Reaction of (η3-2-trifluoromethylvinylcarbene)tricarbonyliron with K[BH(s-Bu)3] or phenyllithium gives (η4-difluorotrimethylenemethane)tricarbonyliron, leaving a fluoride ion. η3-Vinylcarbene complexes react with acetylenes to give η4-cyclopentadiene metal complexes. The reaction proceeds via a metallacyclohexadiene. The complex 1 reacts with an unsaturated metal complex M2Ln to give a binuclear vinylcarbene complex or (η3 : η1-allyl)(Fe–M2). Reaction of 1 with Ru(CO)3(COD) provides a method for selective preparation of (η3 : η1-allyl)(Fe–Ru), which reacts with acetylenes to give [Fe(η4-ruthenacyclohexadiene)(CO)3]. Formation of a η3-vinylcarbene complex by the reaction of a carbene complex with acetylene, and subsequent carbonylation of this complex, is the essential pathway of the Dötz reaction.
An applicability of potassium tetracarbonylhydridoferrate as a reducing reagent to synthesis of primary amines from a wide variety of nitro and nitroso compounds has been examined. The reaction proceeds vigorously and exothermally at room temperature to give the corresponding amines in excellent yields. For nitroaryls, some substituents have interfering effect on the formation of amines. o-Nitrocinnamic aldehyde gives quinoline.
