1520-50-9Relevant articles and documents
Controlling the Activity of a Caged Cobalt-Porphyrin-Catalyst in Cyclopropanation Reactions with Peripheral Cage Substituents
Mouarrawis, Valentinos,Bobylev, Eduard O.,de Bruin, Bas,Reek, Joost N. H.
, p. 2890 - 2898 (2021)
In this study, three novel cubic cages were synthesized and utilized to encapsulate a catalytically active cobalt(II) meso-tetra(4-pyridyl)porphyrin guest. The newly developed caged catalysts (Co-G@Fe8(Zn-L ? 1)6, Co-G@Fe8(Zn-L ? 2)6 and Co-G@Fe8(Zn-L ? 3)6) can be easily synthesized and differ in exo-functionalization, which are either none, polar or apolar groups. This leads to a different polarity of the peripheral environment surrounding the cage, which affects the (relative) local concentration of the substrates surrounding the cage and hence indirectly influences the substrate availability of the catalysis embedded in the active site of the caged catalyst systems. The resulting increased local substrate concentrations give rise to higher catalytic activities of the respective caged catalyst in metalloradical catalyzed cyclopropanation reactions. Interestingly, the catalytic activity is the highest when the apolar cage catalyst (Co-G@Fe8(Zn-L ? 1)6) is used, and lowest with the polar analog (Co-G@Fe8(Zn-L ? 3)6). In addition, the catalytic activity of the cage without exo-functionalities (Co-G@Fe8(Zn-L ? 2)6) is nearly two times lower than that of Co-G@Fe8(Zn-L ? 1)6 and three times higher than that of Co-G@Fe8(Zn-L ? 3)6, which further demonstrates the effect of the peripheral functionalities on the cyclopropanation reaction.
Cyclopropanation and Diels-Alder reactions catalyzed by the first heterobimetallic complexes with bridging phosphinooxazoline ligands
Braunstein, Pierre,Clerc, Guislaine,Morise, Xavier
, p. 68 - 72 (2003)
The bimetallic complex trans-[(OC)3Fe(μ-LP,N)2Cu]BF 4(2), which contains two bridging phosphinooxazoline ligands, is the first metal-metal bonded six-membered ring system with P,N donors and its crystal structure shows a unique bimetallic cradle conformation. This complex is an efficient catalyst for the cyclopropanation of styrene by ethyl diazoacetate and for the Diels-Alder reaction between cyclopentadiene and methacrolein, these reactions being catalyzed for the first time by heterometallic complexes.
Wittig reagents as metallocarbene precursors: In situ generated monocarbonyl iodonium ylides
Ho, Phyllis E.,Tao, Jason,Murphy, Graham K.
, p. 6540 - 6544 (2013)
A proof of concept study was undertaken to determine the suitability of monocarbonyl iodonium ylides (MCIYs) as metallocarbene precursors. Exposing Wittig reagents to iodosylbenzene results in a pseudo-Wittig reaction that generates MCIYs in situ. These ylides are intercepted by transition-metal catalysts to generate metallocarbenes, which then undergo either dimerization or cyclopropanation reactions with a variety of alkenes. Additionally, the reaction between diazoester-derived metallocarbenes and Wittig reagents afforded cross-coupling products, illustrating a new type of olefination reaction for phosphonium ylides. Monocarbonyl iodonium ylides (MCIYs) represent a possible alternative to the use diazoketones and -esters as metallocarbene precursors. Upon treatment with iodosylbenzene, a Wittig reagent will undergo ylide transfer to generate a MCIY in situ. In the presence of transition-metal catalysts, MCIYs serve as precursors to metallocarbenes, which undergo dimerization or cyclopropanation of alkenes. tfacac = trifluoroacetylacetonate. Copyright
Ruthenium- and rhodium-catalyzed carbenoid reactions of diazoesters in hexaalkylguanidinium-based ionic liquids
Large, Torsten,Mueller, Tobias,Kunkel, Helene,Buck, Stefan,Maas, Gerhard
, p. 347 - 353 (2012)
Hexaalkylguanidinium-based room-temperature ionic liquids were investigated as solvents for the cyclopropanation of styrene with diazoacetates catalyzed by Rh2(OAc)4 or [Ru2(μ-OAc) 2(CO)4]n. While the yields of the formed cyclopropanes are much lower compared to the reactions performed in dichloromethane, the diastereomeric ratio is not significantly affected by the change of the reaction medium. Immobilization of the catalysts is only partially successful. In contrast to this intermolecular reaction, the Ru-catalyzed formation of a β-lactam by an intramolecular carbenoid C-H insertion of an α-methoxycarbonyl-α-diazoacetamide occurs in high yield, similar to the Rh2(OAc)4-catalyzed reaction. The cis → trans isomerization of the resulting 1-tert-butyl-3-methoxycarbonyl-4-phenyl-azetidin- 2-one is accelerated in the ionic liquid N,N-dibutyl-N',N'-diethyl-N'',N''- dihexylguanidin-ium triflate.
Selective carbene transfer to amines and olefins catalyzed by ruthenium phthalocyanine complexes with donor substituents
Cailler, Lucie P.,Kroitor, Andrey P.,Martynov, Alexander G.,Gorbunova, Yulia G.,Sorokin, Alexander B.
supporting information, p. 2023 - 2031 (2021/02/26)
Electron-rich ruthenium phthalocyanine complexes were evaluated in carbene transfer reactions from ethyl diazoacetate (EDA) to aromatic and aliphatic olefins as well as to a wide range of aromatic, heterocyclic and aliphatic amines for the first time. It was revealed that the ruthenium octabutoxyphthalocyanine carbonyl complex [(BuO)8Pc]Ru(CO) is the most efficient catalyst converting electron-rich and electron-poor aromatic olefins to cyclopropane derivatives with high yields (typically 80-100%) and high TON (up to 1000) under low catalyst loading and nearly equimolar substrate/EDA ratio. This catalyst shows a rare efficiency in the carbene insertion into amine N-H bonds. Using a 0.05 mol% catalyst loading, a high amine concentration (1 M) and 1.1 eq. of EDA, a number of structurally divergent amines were selectively converted to mono-substituted glycine derivatives with up to quantitative yields and turnover numbers reaching 2000. High selectivity, large substrate scope, low catalyst loading and practical reaction conditions place [(BuO)8Pc]Ru(CO) among the most efficient catalysts for the carbene insertion into amines.
Iron-Catalyzed Intermolecular Functionalization of Non-Activated Aliphatic C?H Bonds via Carbene Transfer
Rodríguez, Mònica,Font, Gemma,Nadal-Moradell, Joel,Hernán-Gómez, Alberto,Costas, Miquel
supporting information, p. 5116 - 5123 (2020/10/06)
The modification of strong Csp3?H bonds via iron carbene intermediates under mild reaction conditions has been an important challenge with attractive prospective in organic synthesis. In this work, we show the efficient combination of an electrophilic iron catalyst with a lithium Lewis acid for the functionalization of strong Csp3?H bonds of cyclic and linear alkanes by the activation of commercially available ethyl diazoacetate (EDA). The reaction proceeds with good yields, under mild reaction conditions (40 °C) and large excess of substrate is not needed. In addition, excellent activity is observed in the cyclopropanation of challenging aliphatic olefins. (Figure presented.).
