Abstract:A novel type of ring expansion reaction of acetylenylcyclobutanols which involves a dimerization process has been developed. The reaction simply proceeds in the presence of ruthenium catalyst to afford the ring-expanded dimer in moderate yield.
“…The utility of the ruthenium precatalyst [CpRu(CH 3 CN) 3 ]PF 6 ( 16 ) in various alkene−alkyne coupling reactions has been reported extensively in the literature. − This and related [CpRu] complexes are also known to promote several alkyne−alkyne coupling reactions, notably including alkyne trimerization 50-52 and diyne cycloadditions with 1,3-dienes, allylic ethers, other alkenes, nitriles, , isocyanates, isothiocycanates, carbon disulfide, and tricarbonyl compounds . Several alkyne−alkyne dimerizations, other than the one described by us (eq 1), using related catalyst systems have also been described. − …”
Section: Introductionmentioning
confidence: 99%
“…The difficulty of acetate elimination after cycloisomerization likely precludes this possibility. Additionally, the elimination of an “internal” hydroxyl group has precedence in the dimerization of propargylic alcohols using [Cp*Ru(CH 3 CN) 3 ]PF 6 as the catalyst (Scheme ) 12 and with substituted cyclobutylpropargylic alcohols 7 [Cp*Ru(CH 3 CN) 3 ]PF 6 -Catalyzed Dimerization of Propargylic Alcohols …”
Section: Introductionmentioning
confidence: 99%
“…60 Several alkyne-alkyne dimerizations, other than the one described by us (eq 1), 12 using related catalyst systems have also been described. [61][62][63][64][65] We proposed a mechanism for this (eq 1) dimerization based upon ruthenacycopentadiene formation, elimination of a water molecule, re-addition of water to the other side of the ruthenacycle, β-H elimination, and reductive elimination. It appeared to us that only a single molecule of propargylic alcohol should be required, and thus a cross-coupling of alkynes and propargylic alcohols should be possible (Scheme 5).…”
Section: Introductionmentioning
confidence: 99%
“…Additionally, the elimination of an "internal" hydroxyl group has precedence in the dimerization of propargylic alcohols using [Cp*Ru(CH 3 CN) 3 ]PF 6 as the catalyst (Scheme 7) 12 and with substituted cyclobutylpropargylic alcohols. 65 Substrates containing only internal propargylic alcohol functionality can undergo cycloisomerization as well (eq 4).…”
A wide variety of diynols containing tertiary, secondary, and primary propargylic alcohols undergo a cycloisomerization reaction to form dienones and dienals in the presence of a catalytic amount of [CpRu(CH(3)CN)(3)]PF(6). The formation of five- and six-membered rings is possible using this methodology. Secondary diynols react to form single geometrical isomeric dienones and -als. Primary diynols undergo a cycloisomerization as well as a hydrative cyclization process. The utility of primary diynol cycloisomerization is demonstrated in a synthesis of (+)-alpha-kainic acid.
“…The utility of the ruthenium precatalyst [CpRu(CH 3 CN) 3 ]PF 6 ( 16 ) in various alkene−alkyne coupling reactions has been reported extensively in the literature. − This and related [CpRu] complexes are also known to promote several alkyne−alkyne coupling reactions, notably including alkyne trimerization 50-52 and diyne cycloadditions with 1,3-dienes, allylic ethers, other alkenes, nitriles, , isocyanates, isothiocycanates, carbon disulfide, and tricarbonyl compounds . Several alkyne−alkyne dimerizations, other than the one described by us (eq 1), using related catalyst systems have also been described. − …”
Section: Introductionmentioning
confidence: 99%
“…The difficulty of acetate elimination after cycloisomerization likely precludes this possibility. Additionally, the elimination of an “internal” hydroxyl group has precedence in the dimerization of propargylic alcohols using [Cp*Ru(CH 3 CN) 3 ]PF 6 as the catalyst (Scheme ) 12 and with substituted cyclobutylpropargylic alcohols 7 [Cp*Ru(CH 3 CN) 3 ]PF 6 -Catalyzed Dimerization of Propargylic Alcohols …”
Section: Introductionmentioning
confidence: 99%
“…60 Several alkyne-alkyne dimerizations, other than the one described by us (eq 1), 12 using related catalyst systems have also been described. [61][62][63][64][65] We proposed a mechanism for this (eq 1) dimerization based upon ruthenacycopentadiene formation, elimination of a water molecule, re-addition of water to the other side of the ruthenacycle, β-H elimination, and reductive elimination. It appeared to us that only a single molecule of propargylic alcohol should be required, and thus a cross-coupling of alkynes and propargylic alcohols should be possible (Scheme 5).…”
Section: Introductionmentioning
confidence: 99%
“…Additionally, the elimination of an "internal" hydroxyl group has precedence in the dimerization of propargylic alcohols using [Cp*Ru(CH 3 CN) 3 ]PF 6 as the catalyst (Scheme 7) 12 and with substituted cyclobutylpropargylic alcohols. 65 Substrates containing only internal propargylic alcohol functionality can undergo cycloisomerization as well (eq 4).…”
A wide variety of diynols containing tertiary, secondary, and primary propargylic alcohols undergo a cycloisomerization reaction to form dienones and dienals in the presence of a catalytic amount of [CpRu(CH(3)CN)(3)]PF(6). The formation of five- and six-membered rings is possible using this methodology. Secondary diynols react to form single geometrical isomeric dienones and -als. Primary diynols undergo a cycloisomerization as well as a hydrative cyclization process. The utility of primary diynol cycloisomerization is demonstrated in a synthesis of (+)-alpha-kainic acid.
“…The reaction is triggered by a release of the strain in four-membered ring systems, and this transformation has been successfully applied to the cascade process by introducing various unsaturated groups on the cyclobutane ring. The cascade ring expansion reaction of cyclobutanols having isopropenyl, allenyl, acetylenyl, and propargyl 7 groups has been developed by us and other groups during the past decade. However, to the best of our knowledge, there are no examples of the reaction of 1,3-dienylcyclobutanols, which are expected to exhibit a different reactivity compared to that of the other unsaturated groups.…”
[reaction: see text] A novel type of cascade ring expansion process has been developed by the palladium-catalyzed reaction of (Z)-1-(1,3-butadienyl)cyclobutanols with aryl iodides. The reaction proceeds in a stereospecific manner to produce (Z)-2-(3-aryl-1-propenyl)cyclopentanones. It has also been found that regioselective alpha-arylation of alkenyl cyclopentanones proceeds to afford the alpha-arylated cyclopentanones.
Der stetige Bedarf an neuen Chemikalien bei gleichzeitiger Forderung nach umweltfreundlichen Herstellungsmethoden stellt an Synthesechemiker große Anforderungen. Die Maximierung der Syntheseeffizienz durch die Umwandlung einfacher Bausteine in komplexe Zielmoleküle bleibt daher eine grundlegende Aufgabe. In diesem Zusammenhang ist die Verwendung von Ruthenium‐Komplexen als Katalysatoren für mehrere nichtmetathetische Umwandlungen ein vielversprechender Ansatz, denn diese Komplexe ermöglichen den schnellen Aufbau komplexer Moleküle mit hoher Selektivität und Atomökonomie. Zudem zeigen sie häufig ungewöhnliche Reaktivität, und durch das sorgfältige Studium der zugrundeliegenden Mechanismen können neue Reaktionen entwickelt und neue Reaktivitäten entdeckt werden.
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