Quinone imines and aminophenols as precursors of new heterocycles

Radical scavenging activity of sterically hindered catecholate and o-amidophenolate complexes of LSbVPh3 type

“…Nevertheless, the main product of reaction is rather phenoxazine than o-iminoquinone [61]. Oxidation of oamidophenolate 5 can lead to the decoordination of free ligand which is able to undergo intramolecular cyclization to form phenoxazine derivatives [62,63]. Taking into account this fact we can suppose that the increasing number n DPPH is caused by interaction of DPPH radical with products of o-iminoquinone cyclization.…”

“…It is supposed that iminoquinone terminates the cyclic chain process and deactivates alkylperoxyl radicals formed in chain-radical reaction and hydrogen peroxide [70]. Moreover, the product of intramolecular cyclization of o-iminoquinone e phenoxazinyl radical [62,63] e should also reveal a radical scavenger activity.…”

“…The complexes 1e6, 3,6-di-tert-butyl-o-benzoquinone 3,6-DBBQ, 4,6-di-tert-butyl-N-(2,6-di-isopropyl-phenyl)-p-aminophenol (APiPr)H 2 , 4,6-di-tert-butyl-N-(2,6-di-isopropyl-phenyl)-p-iminobenzoquinone IBQ-iPr were prepared according to reported procedures [27e29, 62,80], commercial compounds Ph 3 SbBr 2 (Aldrich), Ph 3 Sb (Aldrich, 99%), trolox (Adrich, 97%), 2,6-di-tert-butyl-4-methylphenol (Fluka, 99.0%), [(C 5 H 5 ) 2 Fe]BF 4 (Aldrich) were used as received. UVevis spectra were recorded on SF-103 spectrophotometer (220e1100 nm).…”

Novel indium(III) complexes with sterically hindered o-iminobenzoquinone

“…The absorption bands in IR spectrum of 2 responsible to C@O and C@N bonds in 2 are shifted to long-wave region in comparison with free imQ (m(C@O, C@N) are 1665, 1628 sm À1 for imQ [11] and 1634, 1613 sm À1 for 2, respectively). The related shifts were observed in IR spectrum of similar zinc (imQ Á ZnI 2 ) and copper ((im-Q) 2 CuBr 2 ) complexes described recently [12].…”

“…The effective magnetic moment was calculated as (5), N(1)-C(2) 1.347(6), C(1)-C(2) 1.449 (7), C(2)-C(3) 1.414 (7), C(3)-C(4) 1.365 (7), C(4)-C(5) 1.410 (7), C(5)-C(6) 1.373 (7), C(6)-C(1) 1.421 (7), O(2)-C(7) 1.287(6), N(2)-C(8) 1.321(6), C(7)-C(8) 1.478 (7), C(8)-C(9) 1.407 (7), C(9)-C(10) 1.348 (7), C(10)-C(11) 1.441 (8), C(11)-C(12) 1.350 (7), C(12)-C(7) 1.428 (7) also occurred in 1 H NMR spectrum of complex 2. All signals of complex 2 protons are shifted to the weak field [10] relative to signals of imQ protons [11]. Signals corresponding to protons of o-iminobenzoquinone ring and N-aryl ring undergo the strongest translation (0.24 and 0.27 ppm for the protons of C(3) and C(5) of imQ ring; 0.17 ppm for protons of N-aryl ring).…”