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The syntheses of a novel trishomocubane hydantoin and its mono- and bis-protected t-Boc derivatives are described. The less nucleophilic N-3' nitrogen of the hydantoin ring is protected first when treated with di-tert-butyl dicarbonate (t-Boc anhydride), possibly owing to steric hindrance by the bulky trishomocubane cage skeleton. More basic conditions were required to form the bis-protected t-Boc hydantoin with the same reagent. The structures of these novel compounds were elucidated with 2D NMR techniques. The proton spectrum of the trishomocubane skeleton is complex owing to major overlap of proton signals. A high-level DFT calculation was used to determine some of the crucial interatomic positions, which assisted with the elucidation of the structures. The assignment of proton and carbon signals of the three structures is described and it differs significantly from each other and also from the trishomocubanol precursor. The bis-Boc hydantoin is required for a more facile hydrolysis to the corresponding trishomocubane amino acid at room temperature.

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A mass spectrometric method for the analysis of aziridines and their 2-chloroethylamine precursors is described. These compounds are characterized by their highly labile interconvertible nature. The capabilities of electron impact and fast atom bombardment (FAB) mass spectrometry as ionizaton techniques for structure confirmation studies were explored. A new technique using FAB mass spectrometry to distinguish between an aziridine and its open-chain precursor is described. INTRODUCTIONDuring an investigation of contraceptive compounds occurring in the shrub Salsola tuberculatiformis Botsch., an active fraction (S2), showing a single symmetrical peak in different high-performance liquid chromatography (HPLC) systems, was isolated in microquantities.' This fraction proved to be highly sensitive to light, heat, alkaline pH and air. Autocatalytic degradation and polymerization occurred very rapidly if appropriate steps were not taken. Decomposition in acidic aqueous medium led to the formation of I-(4-hydroxyphenyl)-2-(methylamino)ethanol (I, Fig. I), also called synephrine. This paper describes the utilization of electron impact (ET) and fast atom b~m b a r d m e n t~,~ (FAB) mass spectrometric techniques for the chemical investigation of S2, a number of structurally related synthetic aziridines and their 2-chloroethylamine precursors.Acetylation of S2 yielded a derivative which, although still labile, showed a reduced tendency to decompose in In an attempt to gain insight into the composition and chemical properties of this active fraction (S2), a series of eight model compounds (IVa-d, Va-d, Fig. 2) was synthesized, purified and the structural integrity of each confirmed by nuclear magnetic resonance (NMR). Compounds IVa and IVb were synthesized from l-phenyl-2-aminoethanol and l-phenyl-2-(methylamino)ethanol according to the method of AppeL7 Treatment of 1-phenyl-2-aminoethanol and l-phenyl-2-(methylamino)-ethanol in chloroform with gaseous hydrochloric acid yielded compounds Va and Vb. Compounds Vc and Vd were obtained from octopamine and synephrine by Mass spectra were recorded on a VG70-70E mass spectrometer equipped with a VG2035 data system. All samples were run under positive ion operating conditions. EI operating conditions were as follows: electron energy 70 eV; filament emission current, 100 FA; source temperature, varied between 80 and 200 OC; acceleration voltage, 4 kV. The magnetic analyser was scanned at a rate of 2 s per decade in the mass range 400-30 Da. Samples were introduced into the ion source using the standard VG heated direct-insertion probe.FAB mass spectra were recorded with an Ion Tech saddle-field gun' employing xenon9 as bombardment gas (8 kV, 1 mA). The mass spectrometer was operated at 6 kV and the magnetic analyser was scanned at a rate of 5 s per decade over the range 500-100 Da. Glycerol," obtained from Fluka, was employed as a matrix, however; 3-nitrobenzylalcohol" proved to be equally suitable. RESULTS A N D DISCUSSIONThe EI and FAB results of this study are summarized in Table ...

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