935-02-4Relevant articles and documents
Cyanide-Free Cyanation of sp2 and sp-Carbon Atoms by an Oxazole-Based Masked CN Source Using Flow Microreactors
Sharma, Brijesh M.,Nikam, Arun V.,Lahore, Santosh,Ahn, Gwang-Noh,Kim, Dong-Pyo
supporting information, (2022/02/25)
This work reports a cyanide-free continuous-flow process for cyanation of sp2 and sp carbons to synthesize aryl, vinyl and acetylenic nitriles from (5-methyl-2-phenyloxazol-4-yl) boronic acid [OxBA] reagent as a sole source of carbon-bound mask
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.
Chemo- And regioselective click reactions through nickel-catalyzed azide-alkyne cycloaddition
Baek, Seung-Yeol,Baik, Mu-Hyun,Choe, Wonyoung,Hong, Sung You,Jeon, Ji Hwan,Jeong, Seo Yeong,Kim, Woo Gyum,Nam, Dongsik
, p. 3374 - 3381 (2020/05/14)
Metal-catalyzed cycloaddition is an expeditious synthetic route to functionalized heterocyclic frameworks. However, achieving reactivity-controlled metal-catalyzed azide-alkyne cycloadditions from competing internal alkynes has been challenging. Herein, we report a nickel-catalyzed [3 + 2] cycloaddition of unsymmetrical alkynes with organic azides to afford functionalized 1,2,3-triazoles with excellent regio- and chemoselectivity control. Terminal alkynes and cyanoalkynes afford 1,5-disubstituted triazoles and 1,4,5-trisubstituted triazoles bearing a 4-cyano substituent, respectively. Thioalkynes and ynamides exhibit inverse regioselectivity compared with terminal alkynes and cyanoalkynes, affording 1,4,5-trisubstituted triazoles with 5-thiol and 5-amide substituents, respectively. Density functional theory calculations are performed for the elucidation of the reaction mechanism. The computed mechanism suggests that a nickellacyclopropene intermediate is generated by the oxidative addition of the alkyne substrate to the Ni(0)-Xantphos catalyst, and the subsequent C-N coupling of this intermediate with an azide is responsible for the chemo- and regioselectivity.
