Reaktionen von Komplexliganden, V. Einschiebung von Aminoacetylenen in Metall‐Carbenkohlenstoff‐Bindungen — eine einstufige stereoselektive Synthese von substituierten Aminovinylcarben‐Liganden

Dötz, Karl Heinz

doi:10.1002/cber.19771100109

Cited by 72 publications

(4 citation statements)

References 17 publications

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“…It is generally understood that dialkyl-substituted alkynes undergo insertion with poor to moderate levels of regioselectivity, although electronically/sterically biased alkynes can prove to be useful exceptions. Indeed, the employment of alkynylsilanes and -stannanes, ethers,10d and amines has been addressed with mixed success; alkynylsilanes are generally poorly regioselective, alkynyl ethers give good selectivity but undergo inefficient cycloaddition, and alkynylamines do not provide benzenoid products. In sharp contrast, alkynylstannanes undergo efficient benzannulation with exquisite levels of selectivity, although the products are prone to protodestannylation.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Novel Quinone Boronic Ester Derivatives via a Highly Regioselective Cr-Mediated Benzannulation Reaction and Their Application in Pd-Catalyzed Coupling Processes

2001

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This paper describes the synthesis and reactivity of a novel class of quinone boronic esters. These compounds are prepared utilizing a highly regioselective Dötz annulation of Fischer carbene complexes with alkynylboronates. All substrates studied to date provided a single regioisomeric arylboronic ester product; the origin of this selectivity is discussed in the context of steric and electronic effects. Additionally, these compounds have been found to undergo Pd-catalyzed coupling reactions with a range of aryl and allyl halides and provides a strategy for the selective and predictable preparation of highly substituted quinones and hydroquinones. Finally, the propensity of this technique to prepare highly functionalized aromatic compounds in an expeditious fashion is demonstrated in the total synthesis of dimeric carbazole (+/-)-bis-N-dimethylbismurrayaquinone-A 33.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Novel Quinone Boronic Ester Derivatives via a Highly Regioselective Cr-Mediated Benzannulation Reaction and Their Application in Pd-Catalyzed Coupling Processes

2001

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“…Thus, four cleanly separated multiplets with the relative intensity of one proton each are observed for all derivatives of 3 and 5 . As a consequence, atropisomerism for 3 and 5 by steric repulsion has to be assumed due to a hindered rotation of the C(R)C(Aryl) 2 moiety around the C 3 −C 4 bond.…”

Section: Resultsmentioning

confidence: 99%

CC-Coupling Reactions of Group 6 Allenylidenes with Ynamines: Formation of New Cyclobutenylidene and Pentatrienylidene Complexes

et al. 1998

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The reaction of the diarylallenylidene complexes [(CO)5MCCC(C6H4R-p)2] (M = Cr (1), W (2); R = H (a), Me (b), OMe (c), NMe2 (d)) with the ynamines MeC⋮CNEt2 and PhC⋮CNEt2 affords two products: alkenylallenylidene (3, 5) and cyclobutenylidene complexes (4, 6). The alkenylallenylidene complexes [(CO)5MCCC(NEt2)C(R‘)C(C6H4R-p)2] (R‘ = Me, M = Cr (3), W (5), R = H (a), Me (b), OMe (c), NMe2 (d); R‘ = Ph, M = Cr (3), R = OMe (e), NMe2 (f)) are formed via cycloaddition of the C⋮C bond of the ynamine to the C2C3 bond of 1 and 2, respectively, and subsequent cycloreversion. The cyclobutenylidene = Me, M = Cr (4), W (6), R = H (a), Me (b), OMe (c), NMe2 (d); R‘ = Ph, M = Cr (4), R = OMe (e), NMe2 (f)) are formed by cycloaddition of the ynamines to the C1C2 bond of 1 and 2. The compounds 3, 4a−c, 5, and 6a−c are stable at room temperature. In contrast, 4d−f and 6d decompose on contact with air, light, or silica. Complex 3d was characterized by an X-ray structural analysis. The product ratios 3/4 and 5/6 strongly depend on the solvent and the substitution pattern of both the allenylidene complexes 1 and 2 and the ynamine. In general, decreasing polarity of the solvent increasingly favors formation of cyclobutenylidene complexes. The solvent dependence indicates that the transition state for the formation of 4 and 6 is significantly less polar than that for the formation of 3 and 5. The ratios 3/4 and 5/6 increase in the series a < b < c < d. Kinetic measurements of the reaction of 1c,d with the ynamines MeC⋮CNEt2 and PhC⋮CNEt2 reveal that the complex pairs 3,4 and 5,6 are formed in parallel pathways with an associative rate-determining step for each. The reactions follow second-order kinetics, first-order in the concentrations of the allenylidene complexes 1,2 and of the ynamines. The activation enthalpies ΔH ⧧ are small, and the activation entropies ΔS ⧧ are strongly negative. ΔS ⧧ is more negative for the formation of the alkenylallenylidene complexes than for the formation of the cyclobutenylidene complexes.

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“…Die spektroskopischen Daten von E-11 wurden aus der Reinsubstanz, die von Z-11 jedoch aus den Spektren der Gemische erhalten. E-11: 'H-NMR (CDC13): 6 = 8.70 (lH, s breit, NH); 7.60, 7.50-7.20, 7.10 (2:6:2; ,,d", m, ,,d"; C6H5); 6.50 (1H, = 8 Hz, 0-CH-N), 3.85 (2H, m, diastereotope OCHz), 1.40 (3H, t, CH3, Et). -13C-NMR (CDCl,): 6 = 260.1 (W=C); 203.1 und 197.8 [1:4, trans-und cis-CO, W(CO),]; 155.6 und 136.3 fie i-C, Ph); 129.6, …”

Section: Experimenteller Teilunclassified

Organische Synthesen mit Übergangsmetall‐Komplexen, 55 5‐Aza‐1‐metalla‐1,3,5‐triene von Chrom und Wolfram sowie deren Cyclisierung zu 2H‐Pyrrol‐Komplexen

1991

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The cis isomers 6 undergo a novel-type cyclization to give 2H-of 1 with benzaldehyde (2) in the prescence of TiC1,/Et3N to pyrrole complexes 8. Triene 5b was characterized by an X-. 3 adds to ray analysis. Wir haben die Untersuchungen an l-Metalla-1,3,5-trienen jetzt auf (die Stickstoff-analogen) 5-Aza-l-metalla-l,3,5-triene ausgedehnt und berichten hier erstmals uber deren Darstellung und Eigenschaften sowie uber Studien zur Cyclisierung solcher Verbindungen zu 2 H-Pyrrol-Komplexen. (besser) von TiC&/Et,N zu 2-Aza-allenyl-Komplexen 3 kondensiert4) (Schema 2). Die Kondensationsprodukte sind stark polarisiert und weisen eine Allen-artige, nahezu lineare CNC-Liganden-K~nfiguration~) auf, die durch Schreibweise 3 (anstelle von 3') adiiquat wiedergegeben wird. Eine ,,Kettenverlangerung" der 3-Aza-l-metalla-1,3-diene 3/3' um zwei Kohlenstoffatome zu 5-Aza-l-metalla-l,3,5-trienen Wir berichteten kurzlich iiber die Darstellung vonReaktionen von 2-Aza-allenyl-Komplexen mit Alkinen sind in letzter Zeit mehrfach beschrieben worden ' I . Sie ergaben unterschiedliche Produkte, wie Pyrrole 5a-d), 3-Hydr~xypyridine'~,~), 2-Hydroxypyrrole' b, und Indene 5d*e).5-Aza-l-metalla-1,3,5-triene wurden als Vorstufen von Pyrrolen postuliert. Wir haben solche Verbindungen jetzt erstmals isoliert und strukturell sowie bezuglich ihrer prinzipiellen Reaktionsmuster charakterisiert.2-Aza-allenyl-Komplexe 3a, b reagieren mit dem I-Aminopropin 4 bereits unter recht milden Bedingungen (20°C, 0.5 -1 h) und liefern die Verbindungen 5 -9 (Schema 3), die chromatographisch getrennt und spektroskopisch bzw. kristallographisch analysiert wurden.Die Reaktion verlauft bei Wolfram einheitlicher als bei Chrom. Aus dem Wolfram-Komplex 3b erhalt man das 5-Chem. Ber. 124 (1991) 2587

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Reaktionen von Komplexliganden, V. Einschiebung von Aminoacetylenen in Metall‐Carbenkohlenstoff‐Bindungen — eine einstufige stereoselektive Synthese von substituierten Aminovinylcarben‐Liganden

Cited by 72 publications

References 17 publications

Synthesis of Novel Quinone Boronic Ester Derivatives via a Highly Regioselective Cr-Mediated Benzannulation Reaction and Their Application in Pd-Catalyzed Coupling Processes

Synthesis of Novel Quinone Boronic Ester Derivatives via a Highly Regioselective Cr-Mediated Benzannulation Reaction and Their Application in Pd-Catalyzed Coupling Processes

CC-Coupling Reactions of Group 6 Allenylidenes with Ynamines: Formation of New Cyclobutenylidene and Pentatrienylidene Complexes

Organische Synthesen mit Übergangsmetall‐Komplexen, 55 5‐Aza‐1‐metalla‐1,3,5‐triene von Chrom und Wolfram sowie deren Cyclisierung zu 2H‐Pyrrol‐Komplexen

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