110162-59-9Relevant articles and documents
Poly(ethylene glycol)s as Ligands in Calcium-Catalyzed Cyclic Carbonate Synthesis
Steinbauer, Johannes,Werner, Thomas
, p. 3025 - 3029 (2017)
Herein the use of CaI2 in combination with poly(ethylene glycol) dimethyl ether (PEG DME 500) as an efficient catalyst system for the addition of CO2 to epoxides is reported. This protocol is based on a nontoxic and abundant metal in conjunction with a polymeric ligand. Fifteen terminal epoxides were converted at room temperature to give the desired products in yields up to 99 %. Notably, this system was also effective for the synthesis of twelve challenging internal carbonates in yields up to 98 %.
Reactions of oxalyl chloride with 1,2-cycloalkanediols in the presence of triethylamine.
Itaya, Taisuke,Iida, Takehiko,Natsutani, Itaru,Ohba, Masashi
, p. 83 - 86 (2002)
The relationship between the product patterns and the configurations of 1,2-cycloheptane- and 1,2-cyclooctanediols 9 in the cyclocondensations with oxalyl chloride in the presence of triethylamine at 0 degrees C has been shown analogous to that obtained for 1,2-disubstituted acyclic ethylene glycols 1: cis-1,2-cyclooctanediol (9f) produced the cyclic oxalate 14f as the major product, while trans-1,2-cycloheptanediol (9e) and trans-1,2-cyclooctanediol (9g) formed the cyclic carbonates 12e, g as the major products. On the other hand, the cyclic oxalates 14a-d were formed as the major products from 1,2-cyclopentane- and 1,2-cyclohexanediols regardless of the configuration. These results can be accounted for by assuming the boat-like transition states for cyclizations of the half esters of comparatively rigid five- and six-membered diols 9a--d. The cyclic oxalates 14a, c may be directly formed through the resulting tetrahedral intermediates from cis-diols (9a,c), and the cyclic carbonates 12a,c as the minor products after ring inversion of the tetrahedral intermediates. The tetrahedral intermediates from the trans-isomers 9b, d cannot undergo ring inversion, producing no traces of the cyclic carbonates 12b, d.
Computer-aided rational design of Fe(iii)-catalysts for the selective formation of cyclic carbonates from CO2 and internal epoxides
Sinha, Indranil,Lee, Yuseop,Bae, Choongman,Tussupbayev, Samat,Lee, Yujin,Seo, Min-Seob,Kim, Jin,Baik, Mu-Hyun,Lee, Yunho,Kim, Hyunwoo
, p. 4375 - 4387 (2017/10/13)
The catalytic mechanism of the cyclic carbonate formation reaction between CO2 and internal epoxides promoted by Fe-salen and the Kleij catalyst was examined in detail to better understand how the catalytic efficiency can be increased. Specifically, we aimed to make the catalyst more chemoselective towards forming cyclic carbonates and preventing the competing side reaction leading to polycarbonates via ring-opening polymerization. A few rational design principles were derived and first tested using computer models based on density functional theory. The most promising candidate that was identified in the computer model was then prepared and found to display significantly enhanced reactivity towards forming the cyclic carbonates, supporting the validity of the mechanistic insights deduced from the computer simulations. We propose that a cyclic carbonate is formed most efficiently via an inner-sphere mechanism where both the CO2 and epoxide substrates utilize the metal center for the key bond forming events. In contrast, the ring-opening polymerization uses an outer-sphere mechanism, where a carbonate attacks and ring-opens the epoxide bound to the metal without engaging the metal directly. These mechanistic differences are exploited to implement a chemoselective catalyst by enhancing the rate of the cyclic carbonate formation reaction while leaving the polymerization pathway largely unaffected.
An in situ formed Ca2+-crown ether complex and its use in CO2-fixation reactions with terminal and internal epoxides
Steinbauer,Spannenberg,Werner
supporting information, p. 3769 - 3779 (2017/08/26)
Herein we report an efficient catalytic system based on readily available calcium iodide and 18-crown-6 ether for the atom economical addition of CO2 to epoxides. 1H NMR experiments revealed the selective in situ formation of a crown ether complex. This catalyst allows the conversion of various terminal epoxides under 1 atm CO2 pressure even at room temperature. Remarkably, a broad range of internal epoxides with various substitution patterns and substituents were smoothly converted which confirms the high efficiency and capability of the protocol. Notably, most of the internal carbonates were synthesized in high yields and diastereoselectivities of up to ≥99%. Furthermore, this system operates under solvent-free conditions without any co-catalysts e.g. onium salts.
