[Pd(Cl)2{P(NC5H10)(C6H11)2}2]-A Highly Effective and Extremely Versatile Palladium-Based Negishi Catalyst that Efficiently and Reliably Operates at Low Catalyst Loadings
作者:Jeanne L. Bolliger、Christian M. Frech
DOI:10.1002/chem.201001201
日期:——
electronically activated, non‐activated, deactivated, stericallyhindered, heterocyclic, and functionalized aryl bromides with various (also heterocyclic) arylzinc reagents, typically within a few minutes at 100 °C in the presence of just 0.01 mol % of catalyst. Aryl bromides containing nitro, nitrile, ether, ester, hydroxy, carbonyl, and carboxyl groups, as well as acetals, lactones, amides, anilines,
[Pd(Cl)2 P(NC 5 H 10)(C 6 H 11)2 } 2 ](1)已通过使市售的[Pd(cod)(Cl)2 ]反应定量制备。室温下在几分钟内在N 2中与易于制备的1-(二环己基膦酰基)哌啶在甲苯中的环辛二烯)。综合大楼1已被证明是极佳的Negishi催化剂,能够将各种电子活化,非活化,失活,空间受阻,杂环和官能化的芳基溴化物与各种(也是杂环的)芳基锌试剂定量偶联,通常在几分钟内即可完成。 100°C,仅存在0.01 mol%的催化剂。含有硝基,腈,醚,酯,羟基,羰基和羧基的芳基溴化物,以及缩醛,内酯,酰胺,苯胺,烯烃,羧酸,乙酸,吡啶和嘧啶已被成功用作偶联伙伴。此外,在两个反应伙伴中都可以容忍电子和空间变化。实验观察强烈表明分子机制是有效的。
Novel Reduction of 2,6-Di-<i>t</i>-butyl-<i>p</i>-quinols with Sodium Borohydride
Reduction of 2,6-di-t-butyl-p-quinols with NaBH4 results unexpectedly in the regio- and stereoselective formation of the corresponding dihydro-p-quinols. The novelreduction occurs via a quinoxyborohydride anion intermediate, which regulates the stereochemistry of the 4- and 6-positions in the products. Aromatization of the products is blocked by the t-butyl groups.
Construction of Vicinal Quaternary Carbons via Cu-catalyzed Dearomative Radical Addition
作者:Naoki Tsuchiya、Takashi Nishikata
DOI:10.1246/cl.190247
日期:2019.7.5
In this paper, we confirmed the dearomative addition of tertiary alkyl radicals onto BHT derivatives to form highly congested vicinal quaternary carbons to produce tert-alkylated styrenes in the pr...
The reactivity of BiV reagents towards very hindered phenols with tert.-butyl groups at 2 and 6 under basic conditions has been studied. Unexpected phenylation at the 4-position and, in several cases, replacement of a tert.-butyl group by phenyl have been observed. The mechanism of these reactions has been discussed.
Aryl Oxalate Derivatives as Convenient Precursors for Generation of Aryloxyl Radicals
作者:Paul M. Lahti、David A. Modarelli、Frank C. Rossitto、Ahmet Levent Inceli、Andrew S. Ichimura、Shyamala Ivatury
DOI:10.1021/jo951696v
日期:1996.1.1
oxalates (DAOs) for unimolecular generation of phenoxyl-based radicals under solution and rigid matrix conditions is described. AOCs are usable for photochemical generation of phenoxyl radicals, but are only conveniently stable as precursors when 2,6-di-tert-butylated derivatives are used. AOBs may be used as thermal precursors to aryloxylradicals, since they typically decompose within 2-3 h at 60-85 degrees
描述了在溶液和刚性基质条件下使用芳氧基草酰氯(AOC),芳氧基草酰叔丁基过氧化物(AOB)和草酸二芳基酯(DAO)来单分子生成苯氧基基团的现象。AOC可用于光化学生成苯氧基自由基,但仅当使用2,6-二叔丁基化衍生物时,才能方便地稳定用作前体。AOB可用作芳氧基的热前体,因为它们通常会在60-85摄氏度下2-3小时内分解以产生酚。(1)H-NMR溶液动力学研究发现,对于苯氧基草酰叔丁基过氧化物的分解,DeltaH()= 31 kcal / mol,DeltaS()= +3.4 cal / mol-K,这与过氧化物键断裂的基本一致一致。AOB和更稳定的DAO也是方便的光化学苯氧基自由基前体。