38513-66-5Relevant academic research and scientific papers
Metal-Free Aerobic Oxidative C–O Coupling of C(sp3)–H with Carboxylic Acids Catalyzed by DDQ and tert-Butyl Nitrite
Pan, Decheng,Pan, Zilong,Hu, Zhiming,Li, Meichao,Hu, Xinquan,Jin, Liqun,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu
, p. 5650 - 5655 (2019/08/20)
The formation of the C–O bond is one of the hot topics in the area of C(sp3)–H bond functionalization. A metal-free oxidative cross-coupling between benzylic C(sp3)–H bond and carboxylic acids has been developed. The reactions were performed with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as the catalyst, tert-butyl nitrite (TBN) as the co-catalyst, and molecular oxygen as the terminal oxidant. A variety of diarylmethanes could be successfully coupled with various carboxylic acids to obtain diarylmethanol esters in good to excellent yields. In addition, 2-benzylbenzoic acids could be converted into phthalides in moderate yields through an intramolecular oxidative cyclization.
Catalytic Electrophilic Alkylation of p-Quinones through a Redox Chain Reaction
Xu, Xiao-Long,Li, Zhi
supporting information, p. 8196 - 8200 (2017/06/30)
Allylation and benzylation of p-quinones was achieved through an unusual redox chain reaction. Mechanistic studies suggest that the existence of trace hydroquinone initiates a redox chain reaction that consists of a Lewis acid catalyzed Friedel–Crafts alkylation and a subsequent redox equilibrium that regenerates hydroquinone. The electrophiles could be various allylic and benzylic esters. The addition of Hantzsch ester as an initiator improves the efficiency of the reaction.
DDQ-catalyzed oxidative C-O coupling of sp3 C-H bonds with carboxylic acids
Yi, Hong,Liu, Qiang,Liu, Jie,Zeng, Ziqi,Yang, Yuhong,Lei, Aiwen
, p. 2143 - 2146 (2013/01/15)
Da-ddy, DDQ: By using catalytic amounts of DDQ combined with MnO 2 as oxidant, an efficient oxidative C-O coupling of benzylic sp 3 C-H bonds with carboxylic acids affords a series of carboxylic esters in 70-98 % yields. A wide range
Copper-catalyzed substitution reactions of acylal with organomanganese reagents
Deshmukh, Madhukar B.,Jadhav, Sunil D.,Kadam, Shashikant V.
, p. 989 - 994 (2008/09/18)
A mild method for the copper-catalyzed substitution of aldehyde acylals with organomanganese reagents is reported. This operationally simple C-C bond-forming protocol uses different Cu(I) catalysts. Acylal from trans-cinnamaldehyde furnishes conjugated addition product when reacted with alkyl and aryl organomanganese reagents in presence of 10 mol % of Cu(NCMe) 2 (PPh3)2[BF4] and 2 equivalent of Me3Si-C1 as an accelerator. This reagent can be efficiently used in the substitution of one acetate group of aromatic acylal to form esters in high yield.
The nature of the transition state in diarylmethyl cation - Nucleophile combination reactions as probed by secondary α-deuterium isotope effects
Van Pham, Thuy,McClelland, Robert A.
, p. 1887 - 1897 (2007/10/03)
Transition-state structures for the carbocation-nucleophile combination reactions of (4-substituted-4′-methoxydiphenyl)methyl cations with water, chloride, and bromide ions in acetonitrile-water mixtures have been investigated by measuring the secondary α-deuterium kinetic and equilibrium isotope effects. Rate constants in the combination direction were measured with laser flash photolysis. Equilibrium constants were measured for the water reaction by a comparison method in moderately concentrated sulfuric acid solutions, for the bromide reaction via the observation of reversible combination, and for the chloride reaction from the ratio of the combination rate constant and the rate constant for the ionization of the diarylmethyl chloride product. The fraction of bond making in the transition state has been calculated as the ratio log (kinetic isotope effect):log (equilibrium isotope effect). For the water reaction, there is 50-65% bond making in the transition state; this is also true for cations that are many orders of magnitude less reactive. The same conclusions, 50-65% bond formation in the transition state independent of reactivity, have previously been made in corre-lations of log kw vs. log KR. Thus, two quite different measures of transition structure provide the same result. The kH:kD values for the halide combinations in 100% acetonitrile are within experimental error of unity. This is consistent with suggestions that these reactions are occurring with diffusional encounter as the rate-limiting step. Addition of water has a dramatic retarding effect on the halide reactions, with rate constants decreasing steadily with increased water content. Small inverse kinetic isotope effects are observed (in 20% acetonitrile:80% water) indicating that carbon-halogen bond formation is rate-limiting. Comparison of the kinetic and equilibrium isotope effects shows ～25 and ～40% bond formation in the transition states for the reactions with bromide and chloride, respectively.
The chemistry of acylals. Part I. The reactivity of acylals towards Grignard and organolithium reagents
Sydnes, Leiv K.,Sandberg, Marcel
, p. 12679 - 12690 (2007/10/03)
Aldehyde acylals have been prepared and reacted with Grignard and alkyllithium reagents. Acylals from formaldehyde furnished complex reaction mixtures when reacted with both reagents. Acylals of other aldehydes gave reaction mixtures that consisted mainly of an ester, generated by replacing one of the carboxy groups with the organic part of the organometallic reagent, and regenerated aldehyde. The esters were formed in the highest yields. Yields above 90% were experienced when the acylals were reacted with Grignard reagents under Barbier conditions.
PREPARATION OF ALKYLARYLCARBINOLS BY MONO-OXIDATION AT THE BENZYLIC POSITION USING 2,3-DICHLORO-5,6-DICYANOBENZOQUINONE (D.D.Q.)
Bouquet, M.,Guy, A.,Lemaire, M.,Guette, J. P.
, p. 1153 - 1158 (2007/10/02)
A new and convenient method for the preparation of alkylarylacetates and alkylarylcarbinols is described.Monooxidation at the benzylic position was performed using 2,3-dichloro-5,6-dicyanobenzoquinone (D.D.Q.) in acetic acid.Good yields of arylcarbinols were obtained under mild conditions.
