Niobium- and zirconium-catalyzed reactions of substituted 2 alkynylamines with Et₂Zn

Abstract

The NbCl5–EtMgBr-catalyzed reaction of N,N-disubstituted 2-alkynylamines with Et2Zn followed by hydrolysis or deuterolysis affords (2Z)-alkenylamines (reduction products of alkyne) in high yields.

Low-Valent Niobium Catalysis for the Polymerization of Electron-Rich Diphenylacetylenes

“…Niobium (Nb), which is one of the group 5 metals, has attracted attention in the field of catalysis because various useful chemical transformations have been realized by Nb catalysis. − High-valent Nb­(V) complexes ( d 0 complexes), such as niobium­(V) chloride (NbCl 5 ), are the most stable forms of Nb like other early transition metals such as vanadium, tantalum, tungsten, and molybdenum, which are often used as catalysts in organic synthesis. − On the other hand, low-valent Nb complexes can be formed as thermally stable species from Nb­(V) compounds and reducing reagents, and such species often catalyze unique reactions in organic synthesis. ,,− Two representative examples of such catalytic reactions are shown in Figure a. In 2006, Fuchibe and Akiyama reported transformation of o -trifluoromethylbiphenyl derivatives into fluorene derivatives via activation of strong C–F bonds catalyzed by the low-valent Nb species formed from NbCl 5 and lithium aluminum hydride (LiAlH 4 ) in situ (Figure a, eq 1) .…”

Solvent dependent ESIPT-based probe for optical recognition of Zr(iv) and Zn(ii)

“…8 Zr compounds have biomedical applications in dental implants and crowns, knee and hip replacements, products used for chronic kidney disease and hyperkalemia, and antiperspirants. Zr is also used as a catalyst for various organic reactions like substitution in 2-alkynylamines using Et 2 Zn, 9 ethylmagnesiation reaction, 10 asymmetric carboalumination, 11 alkene–alkene coupling, 12 heterodehydrocoupling, 13 amidation, 14 hydroalumination, 15 hydrophosphination 16 and regioselective hydrosilation. 17 It has a very minute biological role.…”

NbCl5-Mg Reagent System in Regio- and Stereoselective Synthesis of (2Z)-Alkenylamines and (3Z)-Alkenylols from Substituted 2-Alkynylamines and 3-Alkynylols

“…Hence, the goal of this work is to study the reaction of alkynes having different structures with the Mg–NbCl 5 reagent system. Previously, we have developed a selective method for the EtMgBr–NbCl 5 -catalyzed reduction of substituted 2-alkynylamines with Et 2 Zn [ 49 ]. A limitation of this method is the impossibility of obtaining reduction products from acetylenic alcohols under organozinc synthesis conditions.…”