Process for preparing N-hydrocarbyloxy derivatives of sterically
申请人:Ciba-Geigy Corporation
公开号:US04921962A1
公开(公告)日:1990-05-01
N-hydrocarbyloxy compounds of the formula ##STR1## where E.sub.1, E.sub.2, E.sub.3 and E.sub.4 are independently an organic radical so that the carbon atoms to which they are attached are each a quaternary carbon, R is a hydrocarbon radical and T is a divalent radical are prepared directly by the reaction of the corresponding amine or oxyl compound in a hydrocarbon organic solvent with a hydroperoxide in the presence of a metal carbonyl, metal oxide or metal alkoxide catalyst in high yield and purity. These compounds are useful as light stabilizers in diverse substrate systems.
non-acidic aliphatic and benzylicC(sp3)–H bonds was achieved with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) in a single-step by employing an aryl ketone as a sole catalyst. The transformation was initiated by homolysis of a C(sp3)–Hbond in starting substance by the photo-excited aryl ketone. The derived carbon radical was then promptly trapped by TEMPO leading to the formation of the TEMPO-adduct.
通过使用芳基,用 2,2,6,6-四甲基哌啶-1-氧基 (TEMPO) 一步实现了非酸性脂肪族和苄基 C(sp3)-H 键的光驱动自由基氧基官能化酮作为唯一的催化剂。该转化是通过光激发芳基酮对起始物质中的 C(sp3)-H 键进行均裂而引发的。然后衍生的碳自由基立即被 TEMPO 捕获,导致 TEMPO 加合物的形成。衍生的 TEMPO 加合物作为醇等价物在合成上是通用的,因为它可以很容易地通过氧化转化为相应的酮,并通过还原转化为相应的醇。实现本催化反应的关键依赖于TEMPO独特的三重作用,它充当氧官能团的前体、再生芳基酮的氧化剂以及防止过度氧化的衍生TEMPO加合物的保护基团。
US4921962A
申请人:——
公开号:US4921962A
公开(公告)日:1990-05-01
The Photodynamic Covalent Bond: Sensitized Alkoxyamines as a Tool To Shift Reaction Networks Out-of-Equilibrium Using Light Energy
作者:Martin Herder、Jean-Marie Lehn
DOI:10.1021/jacs.8b03633
日期:2018.6.20
alkoxyamines are coupled to a xanthone unit as triplet sensitizer enabling their reversible photodissociation into two radical species. By studying the photochemical properties of three generations of sensitized alkoxyamines it became clear that the nature and efficiency of tripletenergytransfer from the sensitizer to the alkoxyamine bond as well as the reversibility of photodissociation crucially depends