Tetrahydro ionization potential

Table 27 Vertical Ionization Potentials (eV) of Tetrahydro Heterocycles...

More recently, Muchall and Rademacher <1998JST(471)189> have carried out thermolysis of 3,6-dimethyl-, diethyl-, and dipropyl-substituted l,2,3,6-tetrahydro-l,2,4,5-tetrazine to yield the corresponding N-substituted imi-nes 43a-c (Scheme 1). They utilized photoelectron spectroscopy to detect the intermediates and the products formed. Thus, PS of tetrahydrotetrazines shows no change up to 400 °C but at 450 °C thermolysis takes place and the bands belonging to ethanimine and nitrogen appear. The ionization potential observed is shown in Table 4. 

Table 32 Vertical ionization potentials (eV) of tetrahydro heterocycles...

The tetrahydro-l,3-oxazin-2-one (372) is prepared through the cyclization of the threo form of hydroxycarbamate (371) in contact with mesyl chloride, conversely the erythro isomer is O-sulfinated without undergoing cyclization. The removal of an A-Boc group under basic conditions is unusual, and it is proposed that the selective cyclization of the threo isomer occurs because, in its lowest energy conformation, the proximity of the ethoxycarbonyl group and the mesyloxy unit potentiates the ionization of the latter. Once formed, the mesyloxy anion assists deprotonation of the Boc group and hence the cyclization to the oxazine (Scheme 100) <87H(26)64i, 88H(27)667>. 

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