- Oxidative cleavage of the C=N bond during singlet oxygenations of amidoximates
-
Amidoximes are inert toward singlet oxygen (1O2), however, the photooxygenation of amidoximate anions proceeds smoothly and in high yield to give mixtures of amides and nitriles. The mechanism of these reactions appears to involve carbonyl oxide intermediates. The oxidative cleavage of amidoximates closely resembles the results obtained from nitric oxide synthase (NOS) oxidations of N-hydroxyarginine.
- ?cal, Nüket,Erden, Ihsan
-
p. 4765 - 4767
(2007/10/03)
-
- Azetidines. 5. Reaction of 1,1,3,3-Tetramethyl- and 1-Benzyl-1,3,3-trimethylazetidinium Ions with Butyllithium and Phenyllithium. Deuterium Labeling as a Mechanistic Probe
-
The reactions of 1,1,3,3-tetramethylazetidinium iodide (1) and 1-benzyl-1,3,3-trimethylazetidinium bromide (7) with butyllithium and with phenyllithium were studied in ether.The products from the reaction of 1 with butyllithium were 1,3,3-trimethylpyrrolidine (2), 3,3-dimethyl-4-(methylamino)-1-butene (3), 1-(dimethylamino)-2,2-dimethylheptane (4), neopentylpyrrolidine (5), and 1-(dimethylamino)-2,2-dimethylcyclopropane (6).With phenyllithium, 1 gave 2 and 1-(dimethylamino)-2,2-dimethyl-3-phenylpropane (11).With butyllithium, 7 gave 2-phenyl-1,4,4-trimethylpyrrolidine (8), 1-benzyl-3,3-dimethylpyrrolidine (9), and 1-neopentyl-2-phenylpyrrolidine (10).The reaction of phenyllithium with 7 gave only 8 and 9.Mechanistic information was obtained by labeling 1 with deuterium in three different ways: N-methyl-d3, 2,2-d2, and N-methyl-d3-2,2-d2.A primary kinetic isotope effect of 9.4 was found for the formation of 2 from 1-N-methyl-d3.When 2 was formed from 1-2,2-d2, a secondary kinetic isotope effect of 1.17 was measured.The formation of 4 from 1-2,2-d2 was accompanied by a primary kinetic isotope effect of 4.7, suggesting a carbene intermediate.Ylide carbanions involving decomposition to a carbene carbanion in the formation of 3 and an azomethine ylide in the formation of 5 and 9 are probable intermediates.It is postulated that the azomethine ylides react with ethylene formed from the reaction of butyllithium with the solvent ether by means of a concerted (4 + 2) cycloaddition reaction.A primary kinetic isotope effect of 20 was found for the formation of pentylbenzene from dibenzyldimethylammonium bromide and butyllithium.
- Wills, Max T.,Wills, Irene E.,Dollen, Lawrence Von,Butler, Barry L.,Porter, John,Anderson, Arthur G.
-
p. 2489 - 2498
(2007/10/02)
-