Treatment of 2‐pivaloyl‐1,3‐indandione with hydroxylamine leads to the formation of a pair of isomeric indenoisoxazoles, the product formed dependent upon the cyclization conditions. Under acidic conditions, 8‐t‐butylindeno[1,2‐c]isoxazol‐7‐one (5) is formed while under neutral or basic conditions, an oxime, 2, is generated which may then be cyclized under acidic conditions to give 3‐t‐butylindeno[1,2‐c]isoxazol‐4‐one (4). Although these isomeric indenoisoxazoles may be discriminated by chemical means, we were interested in developing an unequivocal method for distinguishing these and potentially other isomeric pairs by spectroscopic means. A 13C‐nmr based method for the discrimination of these isomers which is based on the utilization of chemical shift arguments and spin‐lattice relaxation data is thus presented.
Treatment of 2‐pivaloyl‐1,3‐indandione (1) with hydroxylamine under acidic conditions, results in formation of 8‐t‐butylindeno[1,2‐c]isoxazol‐7‐one (2) while treatment of the triketone with hydroxylamine at neutral or basic pH gave 6 which upon cyclization gave the isomeric 3‐t‐butylindeno[1,2‐c]isoxazol‐4‐one (7). Compound 7 was readily reduced to amine 12 by treatment with hydrazine or hydrogen over platinum. The amine, although quite unreactive, was converted to 3‐t‐butylindeno[1,2‐c]pyrazol‐4‐one (13) with hydrazine or reduced to 15 and 16 with sodium in liquid ammonia and alcohol. Surprisingly, the amine 3 obtained from isoxazole 2 gave reduction product 15 from a sodium‐liquid ammonia reduction and not the expected product 18. Spectral evidence for each of the structures is discussed.
Der Einfluß des Spin‐Zustands auf die Elektronen‐ übertragungseigenschaften der Titelkomplexe (I) bei Oxidation zu entsprechenden Co(III)‐ bzw. Reduktion zu entsprechenden Co(I)‐Verbindungen wurde durch Bestimmung der reversiblen Halbstufenpotentiale in Aceton und für (Ib) in CH,CI2, Cl‐(CHZ), ‐Cl, Pyridin, Me,C0, PhCN, DMF, MeCN, Me‐CO‐NMe, und DMSO untersucht.
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