33604-55-6Relevant academic research and scientific papers
General Method for the Preparation of Electron-Deficient Imidazo[1,2-a]pyridines and Related Heterocycles
McDonald, Ivar M.,Peese, Kevin M.
supporting information, p. 6002 - 6005 (2016/01/09)
A new annulation method for the preparation of the imidazo[1,2-a]pyridine ring system under mild conditions is presented. Treatment of a 2-aminopyridine with a dimethylketal tosylate in acetonitrile at elevated temperature (80-140°C) in the presence of catalytic Sc(OTf)3 provides the imidazo[1,2-a]pyridine product in good yield. The annulation method is broadly applicable to electron-poor 2-aminopyridines and displays a complementary profile to the classic preparation of the imidazo[1,2-a]pyridine ring system by reaction of a bromoketone with electron-rich and -neutral substrates. The scope of the process and mechanistic considerations are discussed.
A one-pot method synthesis of α-chloroketone dimethyl acetals
Zhou, Zhong-Shi,Li, Li,He, Xue-Han
, p. 633 - 635 (2013/11/06)
A new one-pot method has been developed for the direct preparation of α-chloroketone dimethyl acetals from ketones using ammonium chloride as the source of chlorine and potassium monoperoxysulfate as the oxidant in the presence of trimethyl orthoformate in methanol at room temperature. Ketones which have electron-withdrawing groups on the aryl rings gave the corresponding a-chloroketone dimethyl acetals in moderate to good yields.
One-step conversion of acetophenones to α-haloacetophenone dimethyl acetals using DCDMH/DBDMH and molecular sieve in methanol
Zhou, Bin,Chen, Zizhan,Zheng, Zubiao,Han, Bingbing,Zou, Xinzhuo
experimental part, p. 1445 - 1453 (2012/04/17)
Using DCDMH/DBDMH as N-halo reagent, piperidine as catalyst, and 4-A molecular sieve as water-removing agent, α-haloacetophenone dimethyl acetals were directly obtained from the solvent of methanol. As to the substrates with electronwithdrawing groups, the conversions were 80-100%. Copyright Taylor & Francis Group, LLC.
EQUILIBRIA INVOLVING HEMIKETAL AND KETAL FORMATION FROM 2-HALOGENOACETOPHENONES
Toeke, Laszlo,Keglevich, Gyoergy,Petnehazy, Imre,Szoelloesy, Aron
, p. 103 - 110 (2007/10/02)
1H-, 13C-NMR, GC measurements and some preparative work have been made to determine the hemiketal and ketal concentrations in mixtures of alcohols and 2-halogenoacetophenones.Equilibrium values for these products, as well as the time required to reach the equilibrium in the absence of acid, were found to be surprisingly high.Comparisons of the values with those of chloroacetone have also been accomplished.
Conversion of Aromatic Ketones into α-Arylalkanoic Acids. Oxidation by Thallium(III) and by Halogens
Higgins, Stanley D.,Thomas, Barry C.
, p. 235 - 242 (2007/10/02)
The mechanism by which thallium (III) nitrate oxidises aromatic ketones to α-arylalkanoic acids has been investigated and the role of additives in the system elucidated.It is found that in the absence of additives an organothallium intermediate, most probably the phenacylthallium species BzCH2Tl(NO3)2, persists and that the key to an efficient rearrangement is the ready conversion of this compound into its acetal.Thallium(III) is shown not to be a unique reagent for the oxidation.Other oxidants capable of acting initially as an electrophile and then as a leaving group are equally effective, provided that formation of an acetal is possible.Iodine-silver nitrate in particular offers considerable advantages as reagent over thallium(III).Higher specificity is achieved, unwanted side-reactions can be avoided, and toxicity problems are eliminated.Bromine may be used instead of iodine, but chlorine proves unsatisfactory as an oxidant.
