CuCl/Et₃N-Catalyzed Synthesis of Indanone-Fused 2-Methylene Pyrrolidines from Enynals and Propargylamines

Abstract

An efficient CuCl/EtN-catalyzed tandem reaction for the synthesis of indanone-fused pyrrolidine was developed. In this process, two rings and four bonds are generated in one pot with high atom-economy and step-efficiency. The addition of EtN was found as the key factor for the success of the tandem reaction.

Controllable Site-Selective Construction of 4- and 5-Hydroxyalkyl-Substituted Imidazoles from Amidines, Ynals, and Water

“…The desired product 4 was obtained with the attack of H 2 O (Scheme , path i). On the other hand, for the formation of 5 , 1 and 2 condensed to produce the imine intermediate F , which was activated by the catalyst copper to obtaine intermediate vinylic copper , G . Finally, the intermediate G underwent aromatization and nucleophilic attack of H 2 O to give 5a and regenerated the Cu­(I) catalyst (Scheme , path ii).…”

Tandem Reactions of Ynones: via Conjugate Addition of Nitrogen‐, Carbon‐, Oxygen‐, Boron‐, Silicon‐, Phosphorus‐, and Sulfur‐Containing Nucleophiles

“…They enable the syntheses of a lot of benzoannulated compounds. The 5‐ exo ‐ dig cyclization mode was the preferential one over the Michael‐addition type mechanism –. After the initial addition of indoles, acids, MeOH, or amines, the cyclization occurred, leading to the corresponding 5‐ exo ‐ dig products.…”

“…The 5‐ exo ‐ dig cyclization mode was the preferential one over the Michael‐addition type mechanism –. After the initial addition of indoles, acids, MeOH, or amines, the cyclization occurred, leading to the corresponding 5‐ exo ‐ dig products. For example, in 2017, the Zhu group developed a CuCl/Et 3 N‐catalyzed synthesis of pyrrolidines 91.4 from 2‐alkynylaryl aldehydes and propargyl amines [Eq.…”

Synthesis of the Core Structure of Daphnimacropodines

“…Moreover, the radical-type cyclization using bromoketone 14 gave only very messy results. Next, we sought to employ a Conia-ene-type reaction ,− to construct the pivotal tetrahydropyrrole motif, using silyl enol ether 15 , which was synthesized from 2 in one step (see Supporting Information). Unfortunately, all of the conditions attempted including Au­(I), ,, Ag­(I), , Cu­(I), and tungsten-catalyzed Conia-ene-type reactions using compound 15 resulted in no reaction (Table ).…”

“…Next, we sought to employ a Conia-ene-type reaction ,− to construct the pivotal tetrahydropyrrole motif, using silyl enol ether 15 , which was synthesized from 2 in one step (see Supporting Information). Unfortunately, all of the conditions attempted including Au­(I), ,, Ag­(I), , Cu­(I), and tungsten-catalyzed Conia-ene-type reactions using compound 15 resulted in no reaction (Table ). No trace of the desired compound 16 or compound 1 could be detected (LC-MS and NMR) from the aforementioned attempts.…”