96250-99-6Relevant academic research and scientific papers
Co(salen)-catalyzed tert-butyl hydroperoxide oxidation of tert-butylphenols bearing an unsaturated side chain
Maruyama, Kazushige,Kusukawa, Takahiro,Mashino, Takahiro,Nishinaga, Akira
, p. 3342 - 3349 (2007/10/03)
Co(salen)-catalyzed oxidation of 2,4- and 2,6-di-tert-butylphenols bearing an unsaturated side chain, with tert-butyl hydroperoxide (TBHP) in CH2Cl2 at rt, results predominantly in the formation of tert-butylperoxylated products. The position of tert-butylperoxylation depends on the nature of the unsaturated side chain: predominantly the ortho position for 4-alkynyl-2,6-di-tert-butylphenols, the side chain for 4-alkenyl-2,6-di-tert-butylphenols, and the para position for 4-cyano- or 4-(1-methoxyimino)alkyl-2,6-di-tert-butylphenols as well as 2-alkynyl-, 2-alkenyl-, and 2-cyano-4,6-di-tert-butylphenols. The ortho tert-butylperoxylated products arise mainly from initially formed para tert-butylperoxylated products, by migration of the tert-butylperoxy group.
Oxygenation of tert-Butylphenols with an Unsaturated Side Chain
Nishinaga, Akira,Iwasaki, Hitoshi,Shimizu, Tadashi,Toyoda, Yasushi,Matsuura, Teru
, p. 2257 - 2266 (2007/10/02)
Base- and Co(Salpr)-promoted oxygenations of title compounds have been investigated with a view to obtaining further details concerning controlling factors in regioselective O2 incorporation into phenols.In the oxygenation of 4-alkenyl-2,6-di-tert-butyl- and 2-alkenyl-4,6-di-tert-butylphenols (1 and 12), the reactivity of the substrates and regioselectivity in the O2 incorporation may be interpreted in terms of electronic and steric effects of the alkenyl group as well as association effect of the countercation K+ on the transition-state 26 involving a charge transfer from the substrate anion to O2.With 4-alkynyl-2,6-di-tert-butylphenols (21), dioxygen was incorporated exclusively into the ortho position only when the phenolate anion was associated with K+.On the contrary, in the oxygenation of 1 and 12 with Co(Salpr), O2 was incorporated exclusively into the alkynyl side chain, regardless of the nature of the substituent, whereas with 21, O2 incorporation was distributed to both the ortho and the alkenyl side chain.The substituent-dependent regioselectivity in the oxygenation of phenols with Co(Salpr) is because the reactive phenolate-COIII species undergo homolysis to form phenoxy radical-CoII species reversibly, whose oxygenations compete with each other.When the oxygenation of the anionic species predominates, O2 is incorporated into the ortho position, whereas with the radical species the para and side chain oxydations predominate.
OXYGENATION OF 4-ALKYNYL-2,6-DI-t-BUTYLPHENOLS
Nishinaga, Akira,Iwasaki, Hitoshi,Kondo, Toshiyuki,Matsuura, Teruo
, p. 5 - 8 (2007/10/02)
The oxygenation of 4-alkynyl-2,6-di-t-butylphenols (1) promoted by Co(Salpr) resulted in the dioxygen incorporation predominantly into the side chain, whereas in the oxygenation of 1 with t-BuOK in t-BuOH dioxygen was incorporated exclusively into the ort
