enzymatic meta-cleavage of pyrocatechol, both in alkaline solution (/2,,,=375 nm) as well as in acid solution (Lmax=316 nm). Since 2 is relatively unstable it was treated with NH3 for further characterization by the method of Fujiwara et al.L2'. After 3 days the yellow color RT, 72 h COOH QCOOMe 4 5 had disappeared and, as expected, the spectrum of picolinic acid 4 was obtained. The Rf value was identical with that of authentic picolinic acid, both in the thin-layer chromatography (toluene/dioxane/glacial acetic acid, 9 :2 :O.l) as well as in the HPLC (RP 8, 1% acetic acid). For final proof of the structure, the compound was esterified with methanol/POC13 according to the method described by Klo~a[~]. GC-MS gave a peak whose retention time and mass spectrum (m/z 137, 4%, M + ; 107, 23%, M-CH,O; 79, loo%, M-COOCH2) were identical to those of methyl picolinate 5.The mechanism of the meta-cleavage with K02/DMS0 is still unclear. Since the reaction does not take place under N2 it can be concluded that not only hyperoxide and pyrocatechol but also molecular oxygen must participate, and that not just a simple reaction of hyperoxide and pyrocatechol is involved.Several authors have discussed hyperoxide as a possible form of the reactive oxygen involved in dioxygenase reac-This would infer that the above mentioned reaction could be a model for dioxygenase reactions. Received: September 23, 1983 [Z 568 IE] German version: Angew. Chem. 96 (1984) 67 [I] L. Que, Strucr. Bonding 40 (1980) 39.[2] M.
Mixed Sulfur Diimides Containing Phosphino and Amino SubstituentsThe symmetrically substituted sulfur diimides tBu2E-NSN-EtBu2 (E = P (la), As (lb)) can be cleaved to give the mono-potassium salts [tBulE-NSN]K (E = P (2a), As (2b)). The salt 2a reacts with tBu2AsCl providing the mixed sulfur diimide tBu2P-NSN-AstBu2 (3). Chalcogens such as sulfur, selenium, and tellurium add specifically at the phosphorus Im folgenden berichten wir nun uber die Synthese des gemischten Schwefeldiimids tBu2P-NSN -AstBu2 (3) und dessen Reaktion mit Chalkogenen.
Darstellung der Salze [tBu,E-NSNIK (E = P (2a), As (2b))Die Monokalium-Salze 2a, b sollten sich aus den symmetrisch substituierten Schwefeldiimiden S(N-E~BU*)~ la,b durch nucleophile Spaltung entweder der E-N-Bindung (mit KOtBu) oder der S=N-Bindung (mit KNH2) herstellen lassen. Die Reaktion mit Kaliumamid ist eine ,,Umimidierung", wie sie bereits zur Darstellung der Monokalium-Salze [tBu -NSNIK und [Me3Si -NSNIK aus den entsprechenden Schwefeldiimiden S(N-~B u )~ bzw. S(N -SiMe& angewandt wurde').Da die As-N-Bindung in 1 b leicht gespalten wird, 1aBt sich das Salz [tBu2As-NSN]K (2b) bei der Reaktion mit Kalium-tert-butylat glatt erhalten. Dagegen muD bei der Synthese von 2a die Umimidierung mit Kaliumamid gewahlt werden, die iiber die Spaltung einer S = N-Doppelbindung in 1 a verlauft.
The unstable parent compound of the sulfur diimides, S(NH)2 (1), has been obtained in solution by stoichiometric protonation of the anion SN22- in K2SN2 with acetic acid. An analogous protonation of the salts S(NR)(NK) leads to the m onosubstituted sulfur diimides S(NR)(NH) containing bulky substituents such as R = tert-butyl (2) and R = trimethylsilyl (3); 2 and 3 can be isolated as white solids below -40 °C. The temperature-dependent 1H NMR spectra of 1-3 indicate the presence of two isomers in solution (ratio 4:1) which are reversible interconverted.
Abstract Fragmentation of bis(rm-butyl) sulfur diimide, S(NBut)2 (1a), in the presence of Ru3(CO)12 leads to a yellow tetrahedrane-type complex Ru2(CO)6(ButNS) (3a) containing tert-butyl sulfur imide as a six-electron ligand. According to the X-ray structure determination the N−S bond (1.716 Å) is arranged perpendicular to the Ru−Ru axis (2.661 Å).
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