7752-00-3Relevant academic research and scientific papers
NIS-catalyzed oxidative cyclization of alcohols with amidines: A simple and efficient transition-metal free method for the synthesis of 1,3,5-triazines
Tiwari, Abhishek R.,Akash,Bhanage, Bhalchandra M.
, p. 10973 - 10976 (2015)
An efficient method for the synthesis of 1,3,5-triazines by NIS-catalyzed oxidative cyclization of alcohols with amidines has been developed. The reaction works smoothly under transition-metal free and phosphine-free conditions to afford a wide range of 1,3,5-triazine derivatives in moderate to good yields. The synthetic methodology was achieved via in situ oxidation of alcohols to aldehydes.
Mechanistic insight into the azo radical-promoted dehydrogenation of heteroarene towards N-heterocycles
Bains, Amreen K.,Adhikari, Debashis
, p. 6309 - 6318 (2020/11/03)
Borrowing hydrogenation-promoted annulations are considered to be important reactions to synthesize wide variety of N-heterocycles. In these processes, the dehydrogenation of saturated heteroarenes in the late stage is generally required to furnish the desired N-heterocycle. However, in a one-pot, multistep heterocycle synthesis, this step is not well elucidated, and the role of the catalyst is not thoroughly understood. Furthermore, the use of copious amount of base at elevated temperatures further complicates this matter and casts doubt on the involvement of the catalyst in heteroarene dehydrogenation. Herein, we report a molecularly defined nickel catalyst, which can perform two annulation reactions under mild conditions (80 °C, 8 h), towards the sustainable synthesis of triazine and pyrimidine. Mechanistically, we clearly describe the important role of the catalyst in promoting the dehydrogenation of heteroarenes. The binding of the saturated heterocycle to the metal catalyst undergoes a pre-equilibrium step (K = 238 at 80 °C), which is followed by a crucial hydrogen atom transfer. A series of kinetics experiments including Van't Hoff, Eyring analysis and interception of pyrimidinyl radical disclosed the details of the dehydrogenation process. This ligand-driven, base metal catalytic approach is significantly different from the considerably evaluated metal-ligand cooperative bond activation strategies, which may offer an alternative dehydrogenation pathway that demands less energy. This journal is
IEDDA Reaction of the Molecular Iodine-Catalyzed Synthesis of 1,3,5-Triazines via Functionalization of the sp3 C-H Bond of Acetophenones with Amidines: An Experimental Investigation and DFT Study
Tiwari, Abhishek R.,Nath, Shilpa R.,Joshi, Kaustubh A.,Bhanage, Bhalchandra M.
, p. 13239 - 13249 (2017/12/26)
The present work reports an inverse electron demand Diels-Alder (iEDDA)-type reaction to synthesize 1,3,5-trizines from acetophenones and amidines. The use of molecular iodine in a catalytic amount facilitates the functionalization of the sp3 C-H bond of acetophenones. This is a simple and efficient methodology for the synthesis of 1,3,5-triazines in good to excellent yields under transition-metal-free and peroxide-free conditions. The reaction is believed to take place via an in situ iodination-based oxidative elimination of formaldehyde. DFT calculations at the M062X/6-31+G(d,p) level were employed to investigate the reaction mechanism. Reaction barriers for the cycloaddition as well as a formaldehyde expulsion steps were computed, and a multistep mechanism starting with the nucleophilic attack by benzamidine on an in situ generated imine intermediate has been proposed. Both local and global reactivity descriptors were used to study the regioselectivity of the addition steps.
Polythene glycol (PEG) as a reusable solvent system for the synthesis of 1,3,5-triazines via aerobic oxidative tandem cyclization of benzylamines and N-substituted benzylamines with amidines under transition metal-free conditions
Tiwari, Abhishek R.,Bhanage, Bhalchandra M.
supporting information, p. 144 - 149 (2015/12/31)
A green and highly efficient protocol for the synthesis of 1,3,5-triazines from benzylamines and N-substituted benzylamines with amidines in PEG-600 has been developed. This protocol is transition-metal free, phosphine ligand free and uses inexpensive, easily available molecular oxygen (O2) as an oxidant. A series of 1,3,5-triazines derivatives were synthesized in good to excellent yields in a shorter reaction time. The ease of the product separation and reusability of PEG-600 makes it more environmentally benign and economically affordable for gram-scale synthesis.
Iridium-catalyzed cascade dehydrogenation, ring-closure reaction leading to 2,4,6-triaryl-1,3,5-triazines
Shi, Gang,He, Fei,Che, Youxin,Ni, Caihua,Li, Ying
, p. 380 - 386 (2016/04/20)
An efficient iridium-catalyzed dehydrogenation, ring-closure reaction, has been developed via a cascade sequence, in which [Cp?IrI2]2/Xantphos proved to be the most efficient catalyst for the synthesis of 2,4,6-triaryl-1,3,5-triazines from stable aryl-substituted alcohols and amidines. It was the first case of iridium catalyst successful application in such transformation.
Synthesis of 1,3,5-triazines via Cu(OAc)2-catalyzed aerobic oxidative coupling of alcohols and amidine hydrochlorides
You, Qing,Wang, Fei,Wu, Chaoting,Shi, Tianchao,Min, Dewen,Chen, Huajun,Zhang, Wu
supporting information, p. 6723 - 6727 (2015/06/25)
Cu(OAc)2 was found to be an efficient catalyst for dehydrogenative synthesis of 1,3,5-triazine derivatives via oxidative coupling reaction of amidine hydrochlorides and alcohols in air. Both aromatic and aliphatic alcohols can be involved in the reaction and thirty-three products were obtained with good to excellent yields. Moreover, the use of a ligand, strong base and organic oxidant is unnecessary.
An efficient ruthenium-catalyzed dehydrogenative synthesis of 2,4,6-triaryl-1,3,5-triazines from aryl methanols and amidines
Xie, Feng,Chen, Mengmeng,Wang, Xiaoting,Jiang, Huanfeng,Zhang, Min
supporting information, p. 2761 - 2768 (2014/05/06)
By using [RuCl2(p-Cymene)]2/Cs2CO 3 as an efficient catalyst system, the readily available, inexpensive aryl methanols were firstly employed for dehydrogenative synthesis of aryl substituted 1,3,5-triazine derivatives. Due to the inherent stability of alcohols in contrast with aldehydes, our synthetic protocol is adaptable to a broad substrate scope, there is no need for stringent protection during the whole operation process, and it has the potential to prepare valuable products that are currently inaccessible or challenging to prepare using conventional methods. It is a significantly important complement to the conventional synthetic methodologies. This journal is the Partner Organisations 2014.
