Enantioselectivity in visible light-induced, singlet oxygen [2+4] cycloaddition reactions (type II photooxygenations) of 2-pyridones.
نویسندگان
چکیده
3-Substituted 2-pyridones were enantioselectively (68-90% ee) converted into the respective 3-hydroxypyridine-2,6-diones by a sequence consisting of a template-mediated type II photooxygenation and an acid-catalysed rearrangement.
منابع مشابه
Reversible 1,4-cycloaddition of singlet oxygen to N-substituted 2-pyridones: 1,4-endoperoxide as a versatile chemical source of singlet oxygen.
N-substituted pyridones (1) easily undergo singlet oxygenation to give exclusively the corresponding endoperoxides (2), which decompose to give pyridones again while liberating 1O2 in high yield.
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The emission enhancement behavior and photocleavage activity of a ruthenium(II) arene complex, [(η(6)-p-cymene)Ru(dppn)(py)](2+) (1) (dppn = 4,5,9,16-tetraaza-dibenzo[a,c]naphthacene, py = pyridine), towards DNA were compared with [(η(6)-p-cymene)Ru(bpy)(py)](2+) (2), [Ru(bpy)2(dppz)](2+) (3) and [Ru(bpy)2(dppn)](2+) (4) (bpy = 2,2'-bipyridine, dppz = dipyrido-[3,2-a:2',3'-c]phenazine). It was ...
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Atropisomeric 3,4-dihydro-2-pyridones undergo stereospecific [2+2]-photocycloaddition in solution with high stereoselectivity (ee > 98% and de > 96%) in the product. The chiral transfer during phototransformation was rationalized based on the stability/reactivity of the biradical.
متن کاملSome Borderline Cases of Cycloaddition
Common cases of cycloaddition include concerted (2 + 4) and stepwise (2 + 2) reactions which latter are usually easily recognizable as involving biradicals or dipolar ions. The addition in situ of dichioroketene to 2,4-hexadiene and 2butene is stereospecific, as required by the (2 + 2a) mechanism, but is followed by rapid base-catalysed rearrangement of the resulting 2,2-dichiorocyclobutanones ...
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The cycloaddition of 4-methoxycarbonyl-2(1H)-pyridones to silyloxydienes gave isoquinolone derivatives in reasonable yields. Furthermore, the cycloaddition of 6-methoxycarbonyl-2(1H)-pyridones to 2,3-dimethyl-1,3-butadiene produced cycloadducts (isoquinolone and quinolone derivatives) and double cycloadducts (phenanthridone derivatives). The activation energies using Gaussian 98 with RHF/3-21G ...
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ورودعنوان ژورنال:
- Chemical communications
دوره 48 82 شماره
صفحات -
تاریخ انتشار 2012