94575-23-2Relevant articles and documents
Fe-Catalyzed Pictet-Spengler-Type Cyclization via Selective Four-Electron Reductive Functionalization of CO2
Li, Wen-Duo,Chen, Jie,Zhu, Dao-Yong,Xia, Ji-Bao
supporting information, p. 614 - 620 (2021/02/12)
Herein, we describe a novel catalytic Pictet-Spengler-type cyclization using CO2 as a nontoxic and sustainable C1 feedstock with environmentally benign and non-precious-metal iron as catalyst. The reaction is achieved by selective four-electron reduction of CO2 into methylene level intermediate through carefully tuning the reaction parameters. A variety of tetrahydro-β-carbolines and other nitrogen-containing heterocycles can be easily obtained under mild conditions. Mechanistic studies have shown that tetrahydro-β-carbolines are probably obtained via spiroindolenine intermediates.
Access to Spirocyclized Oxindoles and Indolenines via Palladium-Catalyzed Cascade Reactions of Propargyl Carbonates with 2-Oxotryptamines and Tryptamines
Nibbs, Antoinette E.,Montgomery, Thomas D.,Zhu, Ye,Rawal, Viresh H.
, p. 4928 - 4941 (2015/06/02)
(Chemical Equation Presented). Reported here are methods for the direct construction of a range of spirocyclized oxindoles and indolenines in good to excellent yields. Specifically, we report the palladium-catalyzed reactions of oxindoles and indoles, both functioning as bis-nucleophiles, with propargyl carbonates to afford spirocyclic products having an exocyclic double bond on the newly formed ring. The reaction proceeds through a process wherein the first nucleophilic unit on the oxindole or indole reacts with an allenyl-palladium species, formed from oxidative addition of Pd(0) to propargyl carbonates, to generate a π-allyl palladium intermediate that then reacts further with the second nucleophilic component of the oxindole or indole. The cascade process forges two bonds en route to spirocyclized oxindole and indolenine products. The use of chiral phosphines renders the cyclization sequence enantioselective, providing spirocyclic products with modest to good enantioselectivities.
Synthesis of functionalized pyrrole and indole derivatives through carbometallation of lithiated double bonds
Fananas, Francisco J.,Granados, Alejandro,Sanz, Roberto,Ignacio, Jose M.,Barluenga, Jose
, p. 2896 - 2907 (2007/10/03)
Bis(2-lithioallyl)amines derived from bis(2-bromoallyl)amines undergo intramolecular carbometallation of a lithiated double bond, giving dilithiated dihydropyrroles. The cyclizations are promoted by N,N,N′,N′-tetramethylethylenediamine (TMEDA). Reaction of these intermediates with electrophiles allows the preparation of some new fused and nonfused five-membered functionalized heterocycles. Although 2-lithioallylamines do not suffer intermolecular carbometallation, dimerization products are obtained with their copper or zirconium derivatives. Finally, the application of this new reaction to 2-lithio-N-(2-lithioallyl)anilines leads to 3-lithiomethylindole derivatives, which are transformed to functionalized indole derivatives by reaction with electrophiles.
