67174-30-5Relevant academic research and scientific papers
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
Piperidenylmethylidene phosphonylamidines
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, (2008/06/13)
A process for the preparation of carboxylic acids represented by a formula STR1 wherein R1 represents hydrogen atom or a lower alkyl radical, R2 represents hydrogen atom, lower alkyl or allyl radical and R3 represents phenyl, substituted phenyl, substituted naphthyl, dibenzofuranyl or substituted biphenyl. Following novel enamine and amidine compounds as intermediates for manufacturing the carboxylic acids and processes for the manufacture of said enamine and amidine compounds STR2 wherein R1, R2 and R3 represent the meanings as referred to and R4 represents dimethylamino, pyrrolidyl, piperidyl or morpholyl.
