40940-64-5Relevant academic research and scientific papers
Enantioselective Nickel-Catalyzed Alkyne-Azide Cycloaddition by Dynamic Kinetic Resolution
Liu, En-Chih,Topczewski, Joseph J.
, p. 5308 - 5313 (2021/05/04)
The triazole heterocycle has been widely adopted as an isostere for the amide bond. Many native amides are α-chiral, being derived from amino acids. This makes α-N-chiral triazoles attractive building blocks. This report describes the first enantioselective triazole synthesis that proceeds via nickel-catalyzed alkyne-azide cycloaddition (NiAAC). This dynamic kinetic resolution is enabled by a spontaneous [3,3]-sigmatropic rearrangement of the allylic azide. The 1,4,5-trisubstituted triazole products, derived from internal alkynes, are complementary to those commonly obtained by the related CuAAC reaction. Initial mechanistic experiments indicate that the NiAAC reaction proceeds through a monometallic Ni complex, which is distinct from the CuAAC manifold.
Enantioselective Copper Catalyzed Alkyne-Azide Cycloaddition by Dynamic Kinetic Resolution
Liu, En-Chih,Topczewski, Joseph J.
, p. 5135 - 5138 (2019/03/29)
The copper(I) catalyzed alkyne-azide cycloaddition (CuAAC), a click reaction, is one of the most powerful catalytic reactions developed during the last two decades. Conducting CuAAC enantioselectively would add a third dimension to this reaction and would
(Guanidine)copper Complex-Catalyzed Enantioselective Dynamic Kinetic Allylic Alkynylation under Biphasic Condition
Cui, Xi-Yang,Ge, Yicen,Tan, Siu Min,Jiang, Huan,Tan, Davin,Lu, Yunpeng,Lee, Richmond,Tan, Choon-Hong
supporting information, p. 8448 - 8455 (2018/06/22)
Highly enantioselective allylic alkynylation of racemic bromides under biphasic condition is furnished in this report. This approach employs functionalized terminal alkynes as pro-nucleophiles and provides 6- and 7-membered cyclic 1,4-enynes with high yields and excellent enantioselectivities (up to 96% ee) under mild conditions. Enantioretentive derivatizations highlight the synthetic utility of this transformation. Cold-spray ionization mass spectrometry (CSI-MS) and X-ray crystallography were used to identify some catalytic intermediates, which include guanidinium cuprate ion pairs and a copper-alkynide complex. A linear correlation between the enantiopurity of the catalyst and reaction product indicates the presence of a copper complex bearing a single guanidine ligand at the enantio-determining step. Further experimental and computational studies supported that the alkynylation of allylic bromide underwent an anti-SN2′ pathway catalyzed by nucleophilic cuprate species. Moreover, metal-assisted racemization of allylic bromide allowed the reaction to proceed in a dynamic kinetic fashion to afford the major enantiomer in high yield.
Copper-catalyzed allylation of a,a-difluoro-substituted organozinc reagents
Zemtsov, Artem A.,Kondratyev, Nikolay S.,Levin, Vitalij V.,Struchkova, Marina I.,Dilman, Alexander D.
, p. 818 - 822 (2014/04/03)
A method for the coupling of organozinc reagents, difluorocarbene, and allylic electrophiles is described. The reaction involves insertion of difluorocarbene into the carbon-zinc bond followed by copper-catalyzed allylic substitution.
Efficient synthesis and in vitro antitubercular activity of 1,2,3-triazoles as inhibitors of Mycobacterium tuberculosis
Shanmugavelan, Poovan,Nagarajan, Sangaraiah,Sathishkumar, Murugan,Ponnuswamy, Alagusundaram,Yogeeswari, Perumal,Sriram, Dharmarajan
supporting information; experimental part, p. 7273 - 7276 (2012/02/04)
Efficient and rapid synthesis of 1,2,3-triazole derivatives has been achieved via Huisgen's 1,3-dipolar cycloaddition between alkyl/arylazides and diethyl/dimethyl acetylenedicarboxylate in excellent yields under solvent-free conditions. The environmentally friendly solvent-free protocol overcomes the limitations associated with the prevailing time-consuming solution phase protocols and affords the triazoles just in 1-3 min. In vitro antitubercular activity of these triazoles was screened against Mycobacterium tuberculosis H37Rv strain. Four of the compounds showed MIC in the range of 1.56-3.13 μg/mL proving their potential activity.
Copper-catalyzed asymmetric allylic alkylation of racemic cyclic substrates: Application of dynamic kinetic asymmetric transformation (DYKAT)
Langlois, Jean-Baptiste,Alexakis, Alexandre
supporting information; experimental part, p. 447 - 457 (2010/06/13)
The copper-catalyzed asymmetric allylic alkylation (AAA) is of great interest in organic synthesis. This reaction was extensively studied using a broad range of substrates, ligands and organometallic reagents. However, the use of racemic substrates was still limited. Although some processes of kinetic resolution are reported in the literature, no examples of quantitative deracemization are described as is the case for the Pd-catalyzed allylic alkylation. We present here a full account of our investigations through the development of the first example of such a process in copper-catalyzed AAA. High enantioselectivities (up to 99% ee), scope of the reaction and mechanistic considerations are reported herein.
Addition of hypobromous acid to 1-phenylcycloalkenes
Ceylan,Findik,Sahin,Kazaz
, p. 2299 - 2303 (2014/05/06)
Reaction of 1-phenylcyclooctene and 1-phenylcycloheptene with N-bromosuccinimide (NBS) in aqueous DMSO gives the corresponding 3-bromo-2-phenylcycloalkenes and 2-phenylcycloalk-2-enols in a ratio of 3: 1. Unlike them, 1-phenylcyclohexene gives a mixture of 3-bromo-2-phenylcyclohexene and 2-bromo-1-phenylcyclohexanol. The oxidation of allylic alcohols with pyridinium chlorochromate afforded the corresponding α,β-unsaturated ketones.
Total syntheses of (-)-mesembrane and (-)-mesembrine via palladium-catalyzed enantioselective allylic substitution and zirconium-promoted cyclization
Mori,Kuroda,Zhang,Sato
, p. 3263 - 3270 (2007/10/03)
4-Arylhexahydroindole derivatives 5 were synthesized from 2-arylcyclohexenyl allylamine derivatives 4, which have a large protecting group on nitrogen, using zirconium-promoted cyclization. Reaction of 4e with Cp2ZrBu2, followed by treatment with MeMgBr and then O2, gave 2a in 63% yield by a one-pot reaction, since the approach of O2 to zirconium was prevented by the aryl group. The total syntheses of (+)-mesembrane and (+)-mesembrine were achieved starting from 2a. To synthesize these natural products in a chiral form, the starting allylamine derivative 24 (80% yield, 86% ee, recrystallized from MeOH, 99% ee with 79% recovery) was prepared from allyl carbonate 22a and N-tosylallylamine 23 using palladium-catalyzed asymmetric amination in the presence of (S)-BINAPO as a chiral ligand. (-)-Mesembrane and (-)-mesembrine were synthesized from this allylamine 24.
Preparation of chiral allylic alcohols using Rhizopus nigricans. Use of the Harada-Nakanishi exciton chirality method for verifying configurational assignments of allylic alcohols
Ito, Satoru,Kasai, Masaji,Ziffer, Herman,Silverton, J.V.
, p. 574 - 582 (2007/10/02)
A series of (R) acyclic and cyclic allylic alcohols was prepared by enantioselective hydrolysis of acetates using Rhizopus nigricans.The configurations of the alcohols formed were established by chemical methods and, in the case of 1,2-benzocyclohepta-1,3
