2732-12-9Relevant academic research and scientific papers
Mechanistic investigations and substrate scope evaluation of ruthenium-catalyzed direct sp3 arylation of benzylic positions directed by 3-substituted pyridines
Dastbaravardeh, Navid,Kirchner, Karl,Schnuerch, Michael,Mihovilovic, Marko D.
, p. 658 - 672 (2013/02/26)
A highly efficient direct arylation process of benzylic amines with arylboronates was developed that employs Ru catalysis. The arylation takes place with greatest efficiency at the benzylic sp3 carbon. If the distance to the activating aryl ring is increased, arylation is still possible but the yield drops significantly. Efficiency of the CH activation was found to be significantly increased by use of 3-substituted pyridines as directing groups, which can be removed after the transformation in high yield. Calculation of the energy profile of different rotamers of the substrate revealed that presence of a substituent in the 3-position favors a conformation with the CH2 group adopting a position in closer proximity to the directing group and facilitating C-H insertion. This operationally simple reaction can be carried out in argon atmosphere as well as in air and under neutral reaction conditions, displaying a remarkable functional group tolerance. Mechanistic studies were carried out and critically compared to mechanistic reports of related transformations.
Aryl bromides and aryl chlorides for the direct arylation of benzylic amines mediated by ruthenium(II)
Dastbaravardeh, Navid,Schnuerch, Michael,Mihovilovic, Marko D.
, p. 2878 - 2890 (2013/06/27)
The ruthenium(II)-catalyzed sp3 C-H bond arylation of benzylic amines with aryl halides is reported. In the present method, aryl iodides and, more importantly, also the cheaper aryl bromides and aryl chlorides can be applied as aryl sources. Additionally, the method does not require elaborate manipulations in a glove box and can be carried out in simple screw cap vials. Potassium pivalate proved to be beneficial for the transformation with aryl bromides or iodides as aryl source, but was not required for aryl chlorides. In the latter case, the addition of PPh3 led to high conversion. 3-Methyl and 3-phenyl pyridine were established as directing groups, and the substituent in the 3-position represents a key structural feature for high conversion. The directing group can be cleaved after the transformation, which allows access to diarylmethylamines. Mechanistic studies were carried out and critically compared to mechanistic reports of related transformations.. Copyright
Preparation of N-alkyl 2-pyridones via a lithium iodide promoted oto N-alkyl migration: Scope and mechanism
Tasker, Sarah Z.,Bosscher, Michael A.,Shandro, Christina A.,Ryu, Keun Ah,Snapper, Gregory S.,Utter, Jarrad M.,Anderson, Carolyn E.,Lanni, Erica L.,Ellsworth, Bruce A.
, p. 8220 - 8230,11 (2020/10/15)
An efficient and inexpensive LiI-promoted O- to N-alkyl migration of 2-benzyloxy-, 2-allyloxy-, and 2-propargyloxypyridines and heterocycles is reported. The reaction produces the corresponding N-alkyl 2-pyridones and analogues under green, solvent-free conditions in good to excellent yields (30 examples, 20-97% yield). This method has been shown to be intermolecular and requires heat and lithium cation to occur.
Synthesis of substituted N-benzyl pyridones via an O- To N-alkyl migration
Lanni, Erica L.,Bosscher, Michael A.,Ooms, Bartel D.,Shandro, Christina A.,Ellsworth, Bruce A.,Anderson, Carolyn E.
, p. 6425 - 6428 (2008/12/21)
(Chemical Equation Presented) A new LiI-promoted O- to N-alkyl migration has been developed for the conversion of O-alkylated 2-hydroxy pyridines, quinolines, and pyrimidines to the corresponding N-alkylated heterocycles in good to excellent yields (57-99%). This method serves as an efficient means for the preparation of N-benzyl pyridones, quinolones, and pyrimidones.
