The alcoholysis of diazasilacyclopentenes 2, easily obtained from glyoxaldiimines 1 with alkali metal and dichlorosilanes, gives either 3-amino-substituted pyrroles 4 or, with only small amounts of alcohol, N-substituted dihydropyrrolo[3,2-b]pyrroles 5. Reduction of 1 with hydrogen in ethanol in the presence of small amounts of a Pd/C catalyst also gives 4 and 5, together with smaller quantities of a 3,4diaminopyrrole 7. With more of the catalyst the formation of the 1,2-diaminoethanes 6 predominates. A single-crystal X-ray diffraction study was performed for the N,N'-di-tert-butyl derivative 5a, which confirms the expected centrosymmetric structure.
From camphor and fenchone chiral N -sulfonyloxaziridines reagents and reaction conditions for this oxidation are deter-(e.g. 7,13) are available that are well-suited for the destructive-mined by a systematic study. Chiral P(II1) and P(V) compounds stereoselective oxidation of P(II1) compounds 16. Optimum can thus be prepared from racemic P(II1) derivatives.
(1 S) - (+)-Fenchone is sulfonated by SO3 or H2SO4/acetic anhydride in the bridgehead methyl group. This could be confirmed by NMR techniques (INADEQUATE). The fenchonesulfonic acid obtained is converted (SOCl2/NH3) to the cyclic fenchonesulfonimide, which can be oxidized to the corresponding oxaziridine, in close analogy to 10-camphorsulfonimide. Improved procedures for this reaction sequences are given. During the treatment of the sulfonic acid with thionyl chloride, a byproduct with a rearranged bicyclic skeleton is observed whose structure has been determined by ozonolytic degradation and NMR techniques. A possible mechanism for this rearrangement is suggested, based on MNDO calculations of the intermediate carbocations. The fenchonesulfonyloxaziridine oxidizes sulfides to chiral sulfoxides with appreciable enantiomeric excess, but very low reaction rate. A comparison with camphor-derived oxaziridines having similar steric requirements is made.
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