148932-08-5Relevant academic research and scientific papers
Studies on the Oxidation of Enamines with Molecular Oxygen. III Oxidation of Some Amino Styrenes
Blau, K.,Burgemeister, I.,Grasnick, J.,Voerckel, V.
, p. 455 - 466 (2007/10/02)
In the oxidation of the amino styrenes 1a - 1j only products of the oxidative attack at the C=C double bond and hydrolysis products are obtained.Aprotic dipolar solvents and the addition of molecular sieve 5A promote the oxygen uptake.The addition of hydroquinone to the oxidation system does not influence the rate of oxygen absorption or the yields of the oxidation products.
New Methods and Reagents in Organic Synthesis. 34. Diphenyl Phosphorazidate (DPPA) as a 1,3-Dipole. A Simple, Efficient Conversion of Alkyl Phenyl Ketones to 2-Phenylalkanoic Acids
Kawai, Nobutaka,Shioiri, Takayuki
, p. 2564 - 2573 (2007/10/02)
Propiophenone (11) was conveniently converted to its enamines 12a-c using boron trifluoride etherate as a catalyst.Reaction of diphenyl phosphorazidate (DPPA) with the enamines 12a-c efficiently afforded the N-phosphorylated amidines 14a-c by the 1,3-dipolar cycloaddition of DPPA to the enamine double bond, followed by the evolution of nitrogen from the intermediate triazoline 13, and 1,2-migration of the phenyl group. 1,3-Dipolar elimination products 15a-c were also formed, though in very low yields.Some chemical properties of the N-phosphorylated amidine 14a, as well as the 1,3-dipolar character of DPPA, were investigated.By the same reaction sequences (enamine formation followed by the 1,3-dipolar cycloaddition of DPPA), some alkyl phenyl ketones 29a-c were conveniently converted to the N-phosphorylated amidines 31a, 31b, and 27 via the enamines 30a-c.However , in the case of acetophenone and its derivatives 33a-c, these reaction sequences proceeded sluggishly.Alkaline hydrolysis of the N-phosphorylated amidines 14a, 31a, 31b and 27 with potassium hydroxide afforded 2-phenylalkanoic acids 25 and 32a-c, respectively, in excellent yields.The overall three-step process of successive treatment of alkyl phenyl ketones (alkylmethyl) with pyrrolidine, DPPA, and potassium hydroxide may provide a new general method for the efficient conversion of alkyl aryl ketones to 2-arylalkanoic acids.Keywords - enamine; diphenyl phosphorazidate; boron trifluoride etherate; 1,3-dipolar cycloaddition; 1,2-migration; N-phosphorylated amidine; alkaline hydrolysis; alkyl aryl ketone; 2-arylalkanoic acid
