Rhenium-Catalyzed Regio- and Stereoselective Addition of Imines to Terminal Alkynes Leading to N-Alkylideneallylamines

Abstract

The reaction of terminal alkynes with imines using ReBr(CO)(5) as a catalyst results in the production of N-alkylideneallylamines and not the conventional propargylamines. The substituent on the imine nitrogen is important, and a diphenylmethyl group gave the best result. The catalytic cycle of this regioselective C-C bond forming reaction appears to involve the formation of an alkynyl rhenium species and subsequent nucleophilic attack of the alkynyl β-carbon atom on the imine carbon to give a vinylidene rhenium species.

Rhenium‐Catalyzed Oxidative Cyanation of Tertiary Amines with TMSCN

“…The Re-Bu complex possesses distorted octahedral geometry, in which the terminal double-bonded oxygen atom is trans to the oxygen atom of one oxazoline ligand, and the chloride atom is trans to the oxygen atom of the another oxazoline ligand. To our delight, upon testing Re-Bu, the yield of 4a improved to 86 % ( [10][11][12][13]. [22] Scheme 1.…”

“…[4] Several examples of metal-based catalysts, such as Ru, [5] Fe, [6] V, [7] and Mo, [8] in the presence of oxidants for the direct oxidative cyanation of tertiary amines have been reported. [11] The low-valent-rhenium-catalyzed regio-and stereoselective addition of imines and indoles to terminal alkynes through new C-C bond formation was independently reported by Fukumoto [12] and Wang. [9] Homogeneous rhenium catalysis owing to its particular reactivity, chemoselectivity, functional group compatibility, and stability has attracted the attention of chemists in the past few years.…”

Rhenium(I)‐Catalyzed Generation of α,β‐Unsaturated Carbene Complex Intermediates from Propargyl Ethers for the Preparation of Cycloheptadiene Derivatives

“…[17] Then 1,5-hydride transfer of the benzylic hydrogen onto the vinylidene carbon followed by elimination of benzaldehyde generates a,b-unsaturated carbene complex intermediate E. [18] This intermediate reacts with siloxydiene to give divinylcyclopropane F,w hich undergoes Cope rearrangement to give the product. Thus,o ne or two of the carbonyl ligands of ReX(CO) 5 are liberated by heating and vinylidene intermediate D is generated by the reaction with propargyl ether.…”

“…Thus,o ne or two of the carbonyl ligands of ReX(CO) 5 are liberated by heating and vinylidene intermediate D is generated by the reaction with propargyl ether. [17] Then 1,5-hydride transfer of the benzylic hydrogen onto the vinylidene carbon followed by elimination of benzaldehyde generates a,b-unsaturated carbene complex intermediate E. [18] This intermediate reacts with siloxydiene to give divinylcyclopropane F,w hich undergoes Cope rearrangement to give the product. [19] In conclusion, av ery concise and practical method for generation of simple a,b-unsaturated carbene complex intermediates is realized by the reaction of easily available propargyl ethers with ac atalytic amount of ReI(CO) 5 .…”

Efficient Anti‐Markovnikov‐Selective Catalysts for Intermolecular Alkyne Hydroamination: Recent Advances and Synthetic Applications

“…The reactive imines generated by hydroamination can also be subjected to Re‐catalyzed alkynylation, as shown by Fukumoto et al,51 to access 2,3‐disubstituted allylamines in three synthetic steps (Scheme ). These 2,3‐disubstituted allylamines are challenging to prepare, with their reported synthesis requiring multiple steps 52.…”