56795-77-8Relevant academic research and scientific papers
Cobalt-Catalyzed Allylic C(sp3)-H Carboxylation with CO2
Michigami, Kenichi,Mita, Tsuyoshi,Sato, Yoshihiro
supporting information, p. 6094 - 6097 (2017/05/08)
Catalytic carboxylation of the allylic C(sp3)-H bond of terminal alkenes with CO2 was developed with the aid of a Co/Xantphos complex. A wide range of allylarenes and 1,4-dienes were successfully transformed into the linear styrylacetic acid and hexa-3,5-dienoic acid derivatives in moderate to high yields, with excellent regioselectivity. The carboxylation showed remarkable functional group tolerability, so that selective addition to CO2 occurred in the presence of other carbonyl groups such as amide, ester, and ketone. Since styrylacetic acid derivatives can be readily converted into optically active γ-butyrolactones through Sharpless asymmetric dihydroxylation, this allylic C(sp3)-H carboxylation showcases a facile synthesis of γ-butyrolactones from simple allylarenes via short steps.
Synthesis and properties of bimetallic Hoveyda-Grubbs metathesis catalysts
Grudzien, Krzysztof,Malinska, Maura,Barbasiewicz, Michal
scheme or table, p. 3636 - 3646 (2012/07/13)
The catalytic activity of ruthenium Hoveyda-Grubbs complexes in olefin metathesis is a function of complex steric and electronic effects acting on initiation and propagation steps. In order to study the π-electron factors influencing the initiation process, we attempted syntheses of bimetallic complexes with common organic ligands bearing two chelate rings. While most of the studied ligand exchange reactions of the isomeric bis-chelating benzene derivatives gave mixtures of unstable complexes, a homodinuclear derivative of 1,4-dimethoxy-2,5-divinylbenzene was sparingly soluble and precipitated from the reaction mixture in a pure form. The complex was studied with spectroscopic and X-ray methods, which confirmed the symmetrical bimetallic structure. However, in model metathesis reactions the catalyst displayed activity very comparable to the related monometallic complexes. This suggests that in the bimetallic system two consecutive initiation processes of the metathesis catalyst (first, bimetallic complex + olefin → monometallic complex + propagating species; second, monometallic complex + olefin → styrene + propagating species) proceed at similar rates and, thus, no cooperativity between the two steps is displayed. Properties of the family of bimetallic complexes were probed with NMR studies, and π-electronic effects operating in the systems were discussed.
Stereoselective isomerisations of 4-(2′,5′-dimethoxyphenyl)-2,5-dimethyl-1,3-dioxolanes and their 2′-chloro-5′-methoxyphenyl analogues. Temperature-dependent diastereoselective formation of isochromanes
Giles, Robin G. F.,Rickards, Rodney W.,Senanayake, Badra S.
, p. 3361 - 3370 (2007/10/03)
Stereoselective isomerisations of rel-(2R,4S,5R)-4-(2′,5′-dimethoxyphenyl)-2,5-dimethyl-1,3-dioxolane 1 and the 2:1 epimeric mixture of rel-(2S,4R,5R)- and rel-(2R,4R,5R)-4-(2′,5′-dimethoxyphenyl)-2,5-dimethyl-1,3-dioxolanes 2 and 3 with titanium tetrachl
Oxocarbons and related compounds. 27. Synthesis of dihydrocyclobuta[a]naphthalene-1,2-diones and cyclobuta[a]naphthalene-1,2-diones via annulation of alkoxy-(1-alkenyl)benzenes with 3-chloro-3-cyclobutene-1,2-dione. Scope and limitations
Schmidt, Arthur H.,Kircher, Gunnar,Spring, Mathias,Hendriok, Markus W.,Kuenz, Christian
, p. 564 - 574 (2007/10/03)
The reaction of alkoxy-(1-alkenyl)benzenes with semisquaric chloride (3) has been investigated systematically. 1,2-Dialkoxy- and 1-alkoxy′-2-alkoxy″-4-(1-alkenyl)benzenes (6a-j) and (11a-i) react with 3 to give the 3,4-dihydrocyclobuta[a]naphthalene-1,2-diones(8a-j) and (12a-i). Treatment of the dihydrocyclobuta[a]naphthalene-1,2-diones with 1.2 equiv. bromine effects dehydrogenation and affords cyclobuta[a]naphthalene-1,2-diones(9a-e) and (13b-f). Any efforts to extend this annulation reaction to dimethoxy-(1-alkenyl)benzenes with the methoxy groups in other than the 1,2-positions, e. g. 14a, b, 16a, b have been unsuccessful. The reaction of 1,2,3-trimethoxy-4-(1-propenyl) [and 4-(1-butenyl)]-benzenes (18a) and (18b) with semisquaric chloride (3) leads to the elimination of HCl and CH3OH and gives 5,6-dimethoxy-3-methyl [and 3-ethyl]-cyclobuta[a]naphthalene-1,2-diones (20a) and (20b). The reaction pathway of this novel annulation reaction is discussed.
High pressure nucleophilic fluoride-ion substitution reactions: Formation of fluoroalkylbenzenes
Gerdes, John M.,Keil, Robert N.,Shulgin, Alexander T.,Mathis, Chester A.
, p. 121 - 129 (2007/10/03)
A series of 1-phenyl-2-tosyloxy- and 1-phenyl-3-tosyloxyalkanes was synthesized and then subjected to tetrabutylammonium fluoride in THF under 15 kbar (1.5 GPa), 8 kbar or 1 bar pressures. The resultant substitution and elimination reaction product distributions were analyzed. The application of pressure enhanced the progress of the fluoride-ion substitution reactions. The degree of selectivity of the one reaction over the other was found to be a function of tosylate substrate structure and the amount of pressure applied. The exclusive formation of fluoroalkanes from 1-phenyl-2-tosyloxyalkane substrates under 15 kbar pressure demonstrated the potential of the pressure method for prospective use in fluorine-18 radiolabelling applications.
