25522-59-2Relevant academic research and scientific papers
Catalytic, contra-Thermodynamic Positional Alkene Isomerization
Occhialini, Gino,Palani, Vignesh,Wendlandt, Alison E.
supporting information, p. 145 - 152 (2022/01/19)
The positional isomerization of C═C double bonds is a powerful strategy for the interconversion of alkene regioisomers. However, existing methods provide access to thermodynamically more stable isomers from less stable starting materials. Here, we report
Synthesis of 2-aryloxy butenoates by copper-catalysed allylic C-H carboxylation of allyl aryl ethers with carbon dioxide
Ueno, Atsushi,Takimoto, Masanori,Hou, Zhaomin
supporting information, p. 2370 - 2375 (2017/03/20)
Efficient synthesis of 2-aryloxy-3-butenoic acid esters by allylic C-H bond carboxylation of allyl aryl ethers with CO2 has been achieved through deprotonative alumination with an aluminium ate compound (iBu3Al(TMP)Li) followed by NHC-copper-catalysed carboxylation of the resulting aryloxy allylaluminum species. Functional groups such as halogens (F, Cl, Br, I), CF3, amino, methylthio, silyloxy and hetero aromatic groups survived the reaction conditions. The regio- and stereoselective transformation (isomerization) of 2-aryloxy-3-butenoate products to (Z)-2-aryloxy-2-butenate isomers has also been achieved in the presence of a catalytic amount of DBU. These transformations thus constitute an efficient protocol for the divergent synthesis of both 2-aryloxy-3- and 2-butenonates from a single allyl aryl ether substrate using CO2 as a C1 building block.
Coupling Reaction of Enol Derivatives with Silyl Ketene Acetals Catalyzed by Gallium Trihalides
Nishimoto, Yoshihiro,Kita, Yuji,Ueda, Hiroki,Imaoka, Hiroto,Chiba, Kouji,Yasuda, Makoto,Baba, Akio
, p. 11837 - 11845 (2016/08/05)
A cross-coupling reaction between enol derivatives and silyl ketene acetals catalyzed by GaBr3took place to give the corresponding α-alkenyl esters. GaBr3showed the most effective catalytic ability, whereas other metal salts such as BF3?OEt2, AlCl3, PdCl2, and lanthanide triflates were not effective. Various types of enol ethers and vinyl carboxylates as enol derivatives are amenable to this coupling. The scope of the reaction with silyl ketene acetals was also broad. We successfully observed an alkylgallium intermediate by using NMR spectroscopy, suggesting a mechanism involving anti-carbogallation among GaBr3, an enol derivative, and a silyl ketene acetal, followed by syn-β-alkoxy elimination from the alkylgallium. Based on kinetic studies, the turnover-limiting step of the reaction using a vinyl ether and a vinyl carboxylate involved syn-β-alkoxy elimination and anti-carbogallation, respectively. Therefore, the leaving group had a significant effect on the progress of the reaction. Theoretical calculations analysis suggest that the moderate Lewis acidity of gallium would contribute to a flexible conformational change of the alkylgallium intermediate and to the cleavage of the carbon?oxygen bond in the β-alkoxy elimination process, which is the turnover-limiting step in the reaction between a vinyl ether and a silyl ketene acetal.
Gallium tribromide catalyzed coupling reaction of alkenyl ethers with ketene silyl acetals
Nishimoto, Yoshihiro,Ueda, Hiroki,Yasuda, Makoto,Baba, Akio
, p. 8073 - 8076 (2012/08/29)
A 'Ga'llant couple: The α-alkenylation of esters was accomplished by GaBr3-catalyzed coupling between alkenyl ethers and ketene silyl acetals. In this reaction system, various alkenyl ethers, including those with vinyl and substituted alkenyl groups, were applicable, and the scope of applicable ketene silyl acetals was sufficiently broad. The mechanism is also discussed. Copyright
Cyclopropanation of benzylidenemalononitrile with dialkoxycarbenes and free radical rearrangement of the cyclopropanes
Merkley,Venneri,Warkentin
, p. 312 - 318 (2007/10/03)
Thermolysis of 2-cinnamyloxy-2-methoxy-5,5-dimethyl-Δ3-1,3,4-oxadiazoline (1a) and the analogous 2-benzyloxy-2-methoxy compound (1b) at 110°C, in benzene containing benzylidenemalononitrile, afforded products of apparent regiospecific addition of methoxycarbonyl and cinnamyl (or benzyl) radicals to the double bond. When the thermolysis of 1a was run with added TEMPO, methoxycarbonyl and cinnamyl radicals were captured. Thermolysis of the 2,2-dibenzyloxy analogue (1c) in the presence of benzylidenemalononitrile gave an adduct that is formally the product of addition of benzyloxycarbonyl and benzyl radicals to the double bond. In this case, a radical addition mechanism could be ruled out, because the rate constant for decarboxylation of benzyloxycarbonyl radicals is very large. A mechanism that fits all of the results is predominant cyclopropanation of benzylidenemalononitrile by the dialkoxycarbenes derived from the oxadiazolines, in competition with fragmentation of the carbenes to radical pairs. The cyclopropanes so formed then undergo homolytic ring-opening to the appropriate diradicals. Subsequent β-scission of the diradicals to afford radical pairs, and coupling of those pairs, gives the final products. Thus, both carbene and radical chemistry are involved in the overall processes.
Dipolar Cycloaddition of 1-Pyrroline 1-Oxide with 2-Aryl-3-butenoates. Application to Prepare Bicyclic Heterocyclic Compounds
Iida, Hideo,Watanabe, Yohya,Kibayashi, Chihiro
, p. 351 - 357 (2007/10/02)
Five- and six-membered ring systems containing a nitrogen atom at the bridgehead position were prepared via dipolar cycloaddition of 1-pyrroline 1-oxide (5) with 2-aryl-3-butenoates.Cycloaddition of 5 with methyl 4,4-dichloro-2--3
