Gasphasen‐Reaktionen, 61¹⁾ Cycloalkanimine 2H‐Azirin, 1‐Azetin, 1‐Pyrrolin, 1‐Piperidein und 3,4,5,6‐Tetrahydro‐2H‐azepin: Darstellung und Photoelektronen‐Spektren^2,3)

Abstract

Zur Darstellung der oligomerisationsfreudigen Cycloalkanimine ( H 2 m N werden folgende Gasreaktionen PE-spektroskopisch optimiert: Fur das Dreiring-Imin 2H-Azirin die heterogene KOR-Dehydrochlorierung von 2-Chlorethylazid mit anschlieknder Thermolyse des entstehenden Vinylazids und fur die grokren Ringe 1-Azetin (n = 2), 1-Pyrrolin (n = 3), 1-Piperidein (n = 4) sowie das siebengliedrige 3,4,5,6-Tetrahydro-2H-azepin die Chlorierung des betreffenden Cycloalkylamins an festem N-Chlorsuccinimid mit darauffolgender KOR-Dehydrochlorierung des gebildeten N-Chlor-Derivates. Die PE-Spektren aller dargestellten Cycloalkanimine werden anhand Geometrie-optimierter MNDO-Berechnungen zugeordnet und ihre Elektronenstrukturen durch Molekiilzustandsvergleich mit steigender Ringgrok sowie mit der isoelektronischen Reihe der Cycloalkene diskutiert. Die thermische RingBffnung von 1-Azetin zu 2-Azabutadien laDt sich mit PE-spektroskopischer Echtzeit-Gasanalytik gut verfolgen; sein lonisationsmuster wird durch Vergleich mit anderen Azabutadienen zugeordnet.

Substituent effects on the structures and energies of isocyanates and imines by ab initio molecular orbital calculations

“…and for the alkenes [eqns. (8), ( 9)], also with no essential difference between the correlations using the HF/6-3 1 G* and the MP2/6-3 1 G* energies. These are illustrated in Figs.…”

2,3,4,5-Tetrahydropyridine (Δ1-piperideine) and its derivatives. Synthesis and chemical properties

“…Treatment of amine 15a with calcium hypochlorite in acetic acid gave the chloro-derivative 16a, which was converted into the trimerised compound 1a (yields 39% ± 64%) by treatment with an ethanolic solution of KOH. 19 ±21 In other studies, 22,23 piperidine and 2-methylpiperidine were converted into the cyclic imines 1a,b on treatment with sodium hypochlorite in water followed by refluxing of the resulting N-chlorinated derivatives 16a,b in a 10% ethanolic solution of potassium hydroxide 22 or in a solution of sodium methoxide in methanol. 23 On treatment with Bu t OCl in ether 17 or THF, 24 the derivatives 15c,d are transformed into the N-chlorinated compounds 16c,d, which react with MeONa in MeOH, triethylamine in Et 2 O 17 or KOH in EtOH and THF 24 to give the D 1 -piperideines 1c,d.…”

“…Gas-phase chlorination of piperidine 15a with N-chlorosuccinimide (47 8C, 10 71 ± 10 72 mm Hg) and gas-phase dehydrochlorination of the resulting N-chloropiperidine 16a (which is formed in 90% yield) over AdOK (Ad is 1-adamantyl) at 2 8C 22 or over Bu t OK at 797 to 777 8C 22,28 have been reported.…”

1- and 2-Azetines via Visible Light-Mediated [2+2]-Cycloadditions of Alkynes and Oximes

“…Cyclic voltammetry ruled out single electron transfer pathways as all the starting materials had redox potentials outside of the range of the photocatalyst used. Since quenching is indicative of interactions between the substrate and the catalyst excited state, this data suggests that both the isoxazoline (22) and alkyne (21,28) reaction components could be sensitized to their triplet state by the photocatalyst, leading to triplet isoxazoline and triplet alkyne in the reaction mixture. As such, initiation of the [2+2] cycloaddition could be taking place from either the triplet state isoxazoline adding into a ground state alkyne, or a triplet state alkyne adding into the ground state isoxazoline.…”

“…19 To explore the full potential of azetine scaffolds, new and improved synthetic methods for their construction are required. Currently available approaches to access 1azetines include -eliminations [20][21][22] (4), thermolysis of cyclopropyl azides [23][24][25] (5), and ring expansion reactions of aziridines 26 (6) (Fig. 1B).…”