Direct observation of .alpha.-hydrogen transfer from alkyl to alkylidyne ligands in (Me3CCH2)3W:CSiMe3. Kinetic and mechanistic studies of alkyl-alkylidyne exchange

1991 ◽  
Vol 113 (16) ◽  
pp. 6082-6090 ◽  
Author(s):  
Kenneth G. Caulton ◽  
Malcolm H. Chisholm ◽  
William E. Streib ◽  
Ziling Xue
Keyword(s):  
Direct Observation ◽  
Hydrogen Transfer ◽  
Mechanistic Studies ◽  
Alkyl Alkylidyne

scholarly journals Intermolecular Diastereoselective Annulation of Azaarenes into Fused N-heterocycles by Ru(II) Reductive Catalysis

2021 ◽  
Author(s):  
He Zhao ◽  
Yang Wu ◽  
Chenggang Ci ◽  
Zhenda Tan ◽  
Jian Yang ◽  
...  
Keyword(s):  
Building Block ◽  
Transfer Rate ◽  
Hydrogen Transfer ◽  
Functional Group ◽  
Critical Role ◽  
Hydride Transfer ◽  
Mechanistic Studies ◽  
Mild Conditions ◽  
Excellent Selectivity ◽  
Coupling Sequence

Abstract Despite the important advances in azaaryl C−H activation/functionalization, reductive functionalization of ubiquitously distributed but weakly reactive azaarenes remains to date a challenge. Herein, by a strategy incorporating a tandem coupling sequence into the reduction of azaarenes, we present a dearomative annulation of azaarenes into promising fused syn-N-heterocycles by combination with a large variety of aniline derivatives and paraformaldehyde under ruthenium(II) reductive catalysis, proceeding with excellent selectivity, mild conditions, and broad substrate and functional group compatibility. Mechanistic studies reveal that the products are formed via hydride transfer-initiated β-aminomethylation and α-arylation of the pyridyl core in azaarenes, paraformaldehyde serves as both the C1-building block and reductant precursor, and the use of Mg(OMe)2 base plays a critical role in determining the reaction chemo-selectivity by lowering the hydrogen transfer rate. The present work opens a door to further develop valuable reductive functionalization of unsaturated systems by taking profit of formaldehyde-endowed two functions.

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