1285665-86-2Relevant academic research and scientific papers
Multicomponent Aromatic and Benzylic Mannich Reactions through C?H Bond Activation
Xavier, Tania,Rayapin, Corinne,Le Gall, Erwan,Presset, Marc
, p. 13824 - 13828 (2019/11/03)
Multicomponent Mannich reactions through C?H bond activation are described. These transformations allowed for the straightforward generation of densely substituted benzylic and homo-benzylic amines in good yields. The reaction involves a reaction between two transient species: an organometallic species, generated by transition-metal-catalyzed sp2 or sp3 C?H bond activation and an in situ generated imine. The use of an acetal as an aldehyde surrogate was found essential for the reaction to proceed. The process could be successfully applied to RhIII-catalyzed sp2 C?H bond functionalization and extended to CuII-catalyzed sp3 C?H bond functionalization.
Rh-catalyzed C-C cleavage of benzyl/allylic alcohols to produce benzyl/allylic amines or other alcohols by nucleophilic addition of intermediate rhodacycles to aldehydes and imines
Zhang, Xi-Sha,Li, Yang,Li, Hu,Chen, Kang,Lei, Zhi-Quan,Shi, Zhang-Jie
supporting information, p. 16214 - 16225 (2013/02/21)
We report three transformations: 1) direct transformation from biarylmethanols into biarylmethylamines; 2) direct transformation from one biarylmethanol into another biarylmethanol; 3) direct transformation from allylic alcohols into allylic amines. These transformations are based on pyridyl-directed Rh-catalyzed C-C bond cleavage of secondary alcohols and subsequent addition to C=X (X=N or O) double bonds. The reaction conditions are simple and no additive is required. The driving force of C-C bond cleavage is the formation of the stable rhodacycle intermediate. Other directing groups, such as the pyrazolyl group, can also be used although it is not as efficient as the pyridyl group. We carried out in-depth investigations for transformation 1 and found that: 1) the substrate scope was broad and electron-rich alcohols and electron-deficient imines are more efficient; 2) as the leaving group, aldehyde had no significant impact on either the C-C bond cleavage or the whole transformation; 3) mechanistic studies (intermediate isolation, in situ NMR spectroscopic studies, competing reactions, isotopic labeling experiments) implied that: i) The C-C cleavage was very efficient under these conditions; ii) there is an equilibrium between the rhodacycle intermediate and the protonated byproduct phenylpyridine; iii) the addition step of the rhodacycle intermediate to imines was slower than the C-C cleavage and the equilibrium between the rhodacycle and phenylpyridine; iv) the whole transformation was a combination of two sequences of C-C cleavage/nucleophilic addition and C-C cleavage/protonation/C-H activation/nucleophilic addition, with the latter being perhaps the main pathway. We also demonstrated the first example of cleavage of an C(alkenyl)-C(benzyl) bond. These transformations showed the exchange (or substitution) of the alcohol group with either an amine or another alcohol group. Like the "group transplant", this method offers a new concept that can be used to directly synthesize the desired products from other chemicals through reorganization of carbon skeletons.
