Chromium Carbene Complexes Research Articles

ChemInform Abstract: Electronic Effects on the Stereochemical Outcome of the Photochemical Reaction of Chromium Carbene Complexes with Imines to Form β‐ Lactams.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: 5‐Methylene‐2‐cyclopentenones as New Formal (2 + 2 + 1) Cycloadducts from (2‐(Dibenzylamino)ethenyl)carbenechromium Complexes and Alkynes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Reaction of a chromium carbene complex with 1-azadienes and the synthesis of trisubstituted pyrroles

Thermolysis of chromium carbene complexes with 1-azadienes leads to formation of trisubstituted pyrroles in good yield.

Metal-Catalyzed Cyclopropene Rearrangements for Benzannulation: Evaluation of an Anthraquinone Synthesis Pathway and Reevaluation of the Parallel Approach via Carbene-Chromium Complexes

Metal-Catalyzed Cyclopropene Rearrangements for Benzannulation: Evaluation of an Anthraquinone Synthesis Pathway and Reevaluation of the Parallel Approach via Carbene-Chromium Complexes

Effect of Alkene Substituents on Molybdenum and Chromium Carbene Complex Mediated Cyclization Reactions

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of Alkene Substituents on Molybdenum and Chromium Carbene Complex Mediated Cyclization ReactionsDaniel F. Harvey, Ellen M. Grenzer, and Peter K. GantzelCite this: J. Am. Chem. Soc. 1994, 116, 15, 6719–6732Publication Date (Print):July 1, 1994Publication History Published online1 May 2002Published inissue 1 July 1994https://doi.org/10.1021/ja00094a030RIGHTS & PERMISSIONSArticle Views270Altmetric-Citations63LEARN 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 InReddit PDF (2 MB) Get e-AlertsSupporting Info (2)»Supporting Information Supporting Information Get e-Alerts

Regioselective formation of allylidenecyclopropanes from Fischer chromiumcarbene complexes and vinylidenecyclopropanes

The reaction of Fischer chromiumcarbene complexes with vinylidenecyclopropanes in refluxing benzene proceeds in a highly regioselective fashion to afford allylidenecyclopropanes.

ChemInform Abstract: Chromium Carbene Complexes in Organic Synthesis: Recent Developments and Perspectives

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of (1,5-Diazabicyclo[4.3.0]nonan-2-ylidene)pentacarbonylchromium and -tungsten Using Reaction of 2-Unsaturated Carbene Complexes with 6-Membered Hydrazine

Abstract The reaction of styryl carbene complexes of chromium and tungsten with 6-membered hydrazine proceeded smoothly to give the bicyclic carbene complexes, together with dehydropiperidazine complexes.

Chromium Carbene Complexes in Organic Synthesis: Recent Developments and Perspectives

Unexpected reaction pathways and products are apparently not the exception for reactions of Fischer carbenes, and full recognition of the whole potential of this type of complex in organic synthesis is still long way off. Among the classic synthetic applications is the Dötz reaction. One of the many new transformations is the successive reaction of complexes 1 with HNMe2 and pent-1-yne to give cyclopenta[b]pyran 2 and the fulvene complex 3.

Tandem Carbene Insertion-Semipinacol Rearrangement of 1-Alkynylcyclobutenols: A Facile Synthesis of 2-Alkenyl-4-cyclopentene-1,3-diones

Reaction of chromium carbene complexes and 1-alkynylcyclobutenols leads to 2-alkenyl-4-cyclopentene-1,3-diones. Initial alkyne insertion affords a highly electrophilic carbene complex, which then undergoes an alkyl shift-ring expansion, ultimately producing 2-alkenyl-4-cyclopentene-1,3-diones

A transition-metal mediated regioselective synthesis of phenyl quinones via sequential benzannulation and cross coupling reactions

A synthetic route for the regioselective synthesis of polysubstituted quinones by the benzannulation and subsequent cross coupling reactions has been developed. Alkenyl chromium carbene complexes undergo regioselective benzannulation with 2-(trimethylsilyl)-1-phenylethyne with oxidative workup to yield silyl quinones which upon iodination with ICI produce iodoquinones. Subsequent Stille's and Suzuki's cross coupling reactions of these iodoquinones yield polysubstituted quinones.

Regioselectivity of photochemical annulations of chromium carbene complexes

The regioselectivity of photochemical benzannulation reactions of chromium biarylcarbene complexes is reported. Excellent selectivity is observed in furyl- and naphthyl-substituted substrates. Interesting ortho verses para selectivity is found in meta substituted (biphenyl)carbene substrates.

Organische Synthesen mit übergangsmetall‐Komplexen, 66. 2‐Aminopyrrole durch Metathese von (β‐Aminovinyl)carben‐Chrom‐ und ‐Wolfram‐Komplexen mit Isocyaniden

Organic Syntheses via Transition Metal Complexes, 66[1]. — 2‐Aminopyrroles by Metathesis of (β‐Aminovinyl)carbene Complexes of Chromium and Tungsten with Isocyanides(β‐Aminovinyl)carbene complexes LnMC(OEt)—CHC(Ph)‐NHR (Z)‐3a—d [LnM = (CO)5Cr, (CO)5W; R = Ph, iPr, CH2Ph] react with two equivalents of isocyanides R1—NC 5 (R = c‐C6H11, t‐C4H9) to give 2‐amino‐3‐ethoxypyrroles 7a—e and isocyanide complexes LnM(R1—NC) 6. The reaction involves the formation of ketenimine complexes by metathesis. These are key intermediates. The pyrroles 7 are easily oxidized by air to give amidines PhN(R1NH)C—C(OEt)CH—COPh 9 (R = c‐C6H11, t‐C4H9). 7a forms a Michael adduct 10a as well as a Diels‐Alder adduct 11a with N‐phenylmaleimide. A 1‐amino‐2‐ethoxybenzene 12a is obtained from 11a by elimination of aniline.

Organische Synthesen mit Übergangsmetall-Komplexen LXV. Aldehyde durch Hydrolyse der MC-Bindung von Alkoxycarben-Chromkomplexen mit Wasser/Urotropin. Ein zweikerniger verbrückter (ß-Amino)vinylcarben-Chromkomplex durch Fragmentierung von Urotropin

The CrC bonds of aryl- and alkenyl(ethoxy)carbene chromium complexes 1a–d are hydrolysed under mild reaction conditions with high chemoselectivity in presence of hexamethylenetetramine (urotropine), 2, to give aldehydes 4a–d and (urotropine)Cr(CO) 5, 3. The alkynyl(ethoxy)carbene chromium complex 1e reacts with urotropine in a completely different fashion and forms a binuclear (ß-amino)vinylcarbene complex, 5, by fragmentation of the urotropine skeleton.

Synthesis of monoquinonyl porphyrins via benzannulation of fischer carbene complexes and palladium catalysed cross coupling reactions.

Meso-para- and meso-meta-monoquinonyl porphyrins were prepared in good yields by bennzannulation of chromium carbene complexes with unsymmetrical alkynyl porphyrins, and palladium-catalysed cross-coupling reaction of 2,5-dimethoxyphenyl boronic acid with unsymmetrical porphyrin aryl triflates, followed by oxidation.

Cycloadditions, 43[1]. Cyclobutanones via Photoreactions of Chromium‐Carbene Complexes with Olefins and Dienes – A Comparison with the Traditional Ketene Method

AbstractPhotolysis of chromium‐carbene complexes 1 in the presence of olefins and dienes yields cyclobutanones 4 and 5 with varying stereoselectivity. Under oxidative conditions lactones 6, 7, 8, and 10 are obtained as byproducts. Thermal reactions of ketenes 3 with olefins and dienes yield the same cyclobutanones with usually equal selectivities. In the case of 2,3‐dihydro‐1,4‐dioxin as olefin, diene 9 is obtained as a byproduct. Cycloaddition reactions of 1a or 3a with 1,2‐dimethylenecyclopentane (11) yield the spirocyclic cyclobutanones 12 and 13. The symmetric ketone 16 and the ketene dimer 17 are formed as additional products upon cycloaddition of ketene 3b to tetraethoxyethylene. Novel α‐(butylthio)cyclobutanones 4j, k, l, m and 5k, l are formed by cycloaddition reactions of the newly prepared compounds 1c and 3c. The ketene dimer 20 is formed by thermal reactions of 3a with olefins. Unusually low stereoselectivities are observed in the case of photolytic reactions of 1c with dienes.

Reaction of chromium (Fischer) carbenes and sulfilimines

The photochemical reactions of alkoxychromium (Fischer) carbenes and sulfilimines lead to imidates in fair to excellent yields. Aromatic, heteroaromatic, and alkylsulfilimines, the latter bearing functional groups such as cyano, sulfone, ether, ester, and dioxolane groups, gave the corresponding imidates in good to excellent yield. However, acyl- and sulfonyl-substituted sulfilimines did not react with chromium carbenes, except for sulfilimines bearing ethoxycarbonyl and phtalimidylamino groups. A variety of differently substituted chromium carbene complexes bearing alkyl, cycloalkyl, styryl, alkyl, and alkynyl groups attached either at the carbene carbon or at the oxygen also gave imidates in good yields. For α,β-unsaturated carbenes, the exclusive 1,2-addition of the sulfimine nitrogen was observed at room temperature, in contrast to the behavior of other nitrogen nucleophiles which are reported to add in 1,4-fashion under these reaction conditions. In turn, optically active imidates of the type ArN=C(OR * )Me [R * = chiral substituent derived from (R)-(+)-1-phenyl-1-butanol, l-(-)-menthol, (1S)-endo-(-)-borneol, and (1R)-(-)-myrtenol] can be prepared efficiently by utilizing the corresponding chiral alkoxy group on the carbene moiety. The reactions above also occur in the dark but reaction times are considerably longer. N-Halosulfilimines reacted with alkoxychromium carbenes to yield N-acylsulfimines instead of the expected N-haloimidates. Based upon a set of thermal and photochemical reactions between N-haloimidates and diphenyl sulfide in the absence of chromium complexes, the complex (CO) 5 CrNCMe is proposed to be responsible for this novel reaction of N-haloimidates and diphenyl sufide

ChemInform Abstract: Cyclopentenone Formation via Hydrogen Activation in the Reactions of Chromium Carbene Complexes with Alkynes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Synthesis of Compounds Containing Two Adjacent 13C Labels by Photolytic Reactions of Chromium Carbene Complexes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Cyclization Reactions of Molybdenum and Chromium Carbene Complexes with 1,6‐ and 1,7‐Enynes: Effect of Tether Length and Composition.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.