38047-66-4Relevant academic research and scientific papers
Borane-Catalyzed Reduction of Pyridines via a Hydroboration/Hydrogenation Cascade
Yang, Zhao-Ying,Luo, Heng,Zhang, Ming,Wang, Xiao-Chen
, p. 10824 - 10829 (2021/09/08)
We have developed a method for a B(C6F5)3-catalyzed hydroboration/hydrogenation cascade reduction of pyridines. The method was particularly effective for 2,3-disubstituted pyridines, which generated piperidines in high yields with high cis selectivity. Mechanistic studies indicated that the pyridine substrates and the piperidine products sequentially acted as bases in cooperation with B(C6F5)3to split H2. The broad functional group tolerance of the method allowed its use for the synthesis of some biologically active molecules.
Direct α-C-H bond functionalization of unprotected cyclic amines
Chen, Weijie,Ma, Longle,Paul, Anirudra,Seidel, Daniel
, p. 165 - 169 (2018/02/06)
Cyclic amines are ubiquitous core structures of bioactive natural products and pharmaceutical drugs. Although the site-selective abstraction of C-H bonds is an attractive strategy for preparing valuable functionalized amines from their readily available parent heterocycles, this approach has largely been limited to substrates that require protection of the amine nitrogen atom. In addition, most methods rely on transition metals and are incompatible with the presence of amine N-H bonds. Here we introduce a protecting-group-free approach for the α-functionalization of cyclic secondary amines. An operationally simple one-pot procedure generates products via a process that involves intermolecular hydride transfer to generate an imine intermediate that is subsequently captured by a nucleophile, such as an alkyl or aryl lithium compound. Reactions are regioselective and stereospecific and enable the rapid preparation of bioactive amines, as exemplified by the facile synthesis of anabasine and (-)-solenopsin A.
B(C6F5)3-Catalyzed Cascade Reduction of Pyridines
Liu, Zhi-Yun,Wen, Zhi-Hui,Wang, Xiao-Chen
supporting information, p. 5817 - 5820 (2017/05/12)
B(C6F5)3 has been found to be an effective catalyst for reduction of pyridines and other electron-deficient N-heteroarenes with hydrosilanes (or hydroboranes) and amines as the reducing reagents. The success of this development hinges upon the realization of a cascade process of dearomative hydrosilylation (or hydroboration) and transfer hydrogenation. The broad functional-group tolerance (e.g. ketone, ester, unactivated olefins, nitro, nitrile, heterocycles, etc.) implies high practical utility.
Borane-Catalyzed Transfer Hydrogenations of Pyridines with Ammonia Borane
Zhou, Qiwen,Zhang, Lanqiong,Meng, Wei,Feng, Xiangqing,Yang, Jing,Du, Haifeng
supporting information, p. 5189 - 5191 (2016/11/02)
With the use of ammonia borane as a hydrogen source, a borane catalyzed metal-free transfer hydrogenation of pyridines was successfully realized for the first time to furnish a variety of piperidines in 44-88% yields with moderate to excellent cis-selecti
Facile denitrosation of Cyclic N-nitrosamines with hydrazoic acid
Ponnuswamy,Akila,Kiruthiga Devi
supporting information, p. 2030 - 2034 (2015/08/18)
A simple and facile method for the denitrosation of cyclic N-nitrosamines using HN3 (concentrated H2SO4+NaN3) is reported. In this method, limited usage of this reagent does not affect the carbonyl group.
Addition of organometallic reagents to chiral N-methoxylactams: Enantioselective syntheses of pyrrolidines and piperidines
Jaekel, Mascha,Qu, Jianping,Schnitzer, Tobias,Helmchen, Guenter
, p. 16746 - 16755 (2014/01/06)
Enantioselective iridium-catalyzed allylic substitutions were used to prepare N-allyl hydroxamic acid derivatives that were suitable for ring-closing metathesis, giving N-methoxylactams. Reactions of these derivatives with Grignard or organolithium compou
Metal-free borane-catalyzed highly stereoselective hydrogenation of pyridines
Liu, Yongbing,Du, Haifeng
supporting information, p. 12968 - 12971 (2013/09/24)
A metal-free direct hydrogenation of pyridines was successfully realized by using homogeneous borane catalysts generated from alkenes and HB(C 6F5)2 via in situ hydroboration. The reaction affords a broad range of piperidines in high yields with excellent cis stereoselectivities.
Diastereoselective access to nonracemic 2-cis-substituted and 2,6-cis-disubstituted piperidines
Coia, Nicolas,Mokhtari, Naima,Vasse, Jean-Luc,Szymoniak, Jan
, p. 6292 - 6295 (2012/01/06)
Access to nonracemic amino ketones via a hydrozirconation/transmetalation/ acylation sequence applied to Boc-protected 1-aminobut-3-enes is presented. This method was applied to the stereoselective synthesis of cyclic imines (or iminiums) which were diastereoselectively converted into 2-cis-substituted and 2,6-cis-disubstituted piperidines. The potential of this approach in the field of alkaloid synthesis was illustrated by the synthesis of (-)-coniine and (-)-indolizidine 209D. Furthermore, access to indolizidines bearing a quaternary center could also be envisioned through this strategy.
Facile diastereoselective reactions of chiral 1,3-oxazolidines with grignard reagents; asymmetric syntheses of 2-substituted and 2,6-disubstituted piperidines
Poerwono, Hadi,Higashiyama, Kimio,Yamauchi, Takayasu,Takahashi, Hiroshi
, p. 385 - 400 (2007/10/03)
(S)- and (R)-2-Phenylpiperidines, (S)- and (R)-2-methylpiperidines, meso- and (2R, 6R)-2,6-diphenylpiperidines, and meso- and (25, 65)-2,6-dimethylpiperidines were synthesized asymmetrically starting from the diastereoselective addition of Grignard reagents to chiral 1,3-oxazolidines, converting of 1-aza-4-oxabicyclo[4.3.0]nonane derivatives as pivotal intermediates.
Conformational analysis of r-2,c-6-diphenylpiperidines by NMR and molecular mechanics methods
Ravindran, T,Jeyaraman, R
, p. 677 - 682 (2007/10/02)
The title compounds 6-10 have been prepared by the Wolf-Kishner reduction of the piperidin-4-ones (1-5) and their stereochemistry investigated by 1H and 13C NMR specteroscopy.Wolf-Kishner reduction of t-3,t-5-dimethyl-r-2,c-6-diphenylpiperidin-4-one (5) l
