88365-72-4Relevant academic research and scientific papers
N-Chlorination and Dehydrochlorination of Aryl-substituted Piperidines, 3-Azabicyclononanes, and 3,7-Diazabicyclononanes. Synthesis of the First 3,7-Diazanoradamantane.
Quast, Helmut,Mueller, Bodo
, p. 3931 - 3946 (2007/10/02)
The N-chloropiperidine derivatives 4b - 6b, 7 and 8 were obtained by N-chlorination using tert-butyl hypochlorite.While dehydrochlorination of 4b and 8 required potassium hydroxide and tert-butoxide, respectively, 5b and 7 eliminated hydrogen chloride at temperatures as low as 20 - 25 deg C even in the absence of base.The N-chloro compound 6b lost hydrogen chloride in boiling chlorobenzene.As expected, the N-chloropiperidine 4b and the N-chloro-3-azabicyclononanes 5b, 6b formed the tetrahydropyridine 9 and the bicyclic iminium chlorides 10 * HCl and 11 * HCl, respectively.The latter were converted into free bases 10 and 11.In contrast, on dehydrochlorination the 3,7-diazabicyclononane ring system of the N,N'- dichloro compound 8 was degraded to the 2,6-bis(4-methylphenyl)pyridine (15).Surprisingly, the spontaneous dehydrochlorination of the 3-chloro-3,7-diazabicyclononane 7 produced the highly strained 3,7-diazanoradamantane 12.Its structure was assigned on the basis of high field proton and carbon-13 NMR spectra, nuclear Overhauser difference spectroscopy, and the temperature dependence of the proton and carbon-13 NMR spectra resulting from slow rotation of the 4-methylphenyl groups.The barrier of rotation for the 1,3-diaxial oriented 4-methylphenyl groups at C-6,8 was found to be ΔG*247 = 50 +/- 1 kJ * mol-1.
