1379005-26-1Relevant academic research and scientific papers
A room-temperature protocol to access isoquinolines through Ag(i) catalysed annulation of o-(1-alkynyl)arylaldehydes and ketones with NH4OAc: Elaboration to berberine and palmatine
Reddy, Virsinha,Jadhav, Abhijeet S.,Vijaya Anand, Ramasamy
, p. 3732 - 3741 (2015)
An efficient and mild protocol for the direct construction of aryl- and alkyl-substituted isoquinolines has been realized through silver nitrate catalyzed aromatic annulation of o-(1-alkynyl)arylaldehydes and ketones with ammonium acetate. The salient feature of this methodology is that this annulation could be effected at room temperature leading to a wide range of isoquinoline derivatives in good to excellent yields. Additionally, this approach has been employed to the synthesis of biologically important isoquinoline alkaloids such as berberine and palmatine.
Light-Enabled Radical 1,4-Aryl Migration Via a Phospho-Smiles Rearrangement
De Abreu, Maxime,Belmont, Philippe,Brachet, Etienne
, p. 3758 - 3767 (2021/02/01)
Rearrangement reactions in organic chemistry are attractive strategies to build efficiently complex scaffolds, in just one step, from simple starting materials. Among them, aryl migrations are certainly one of the most useful and straightforward rearrangement for building attractive carbon-carbon bonds. Of note, anionic aryl migration reactions have been largely described compared to their radical counterparts. Recently, visible-light catalysis has proven its efficiency to generate such radical rearrangements due to the concomitant loss of a particle (often CO2 or SO2), which is the driving-force of the reaction. Here, we disclose a Smiles-type rearrangement, triggered by a phosphorus-containing unit (arylphosphoramidate), therefore called "phospho-Smiles"rearrangement, allowing a Csp2-Csp2 bond formation thanks to a 1,4-aryl migration reaction. In addition, combining this approach with a radical hydroamination/amination reaction produces an amination/phospho-Smiles cascade particularly attractive, for instance, to investigate the synthesis of the phthalazine core, a scarcely described scaffold of interest for medicinal chemistry projects.
Transition-Metal-Free Reverse Reactivity of (2-Alkynyl)-Arylaldimines: Assembly of Functionalized Amino-Indinones
Saini, Kapil Mohan,Saunthwal, Rakesh K.,Sushmita,Verma, Akhilesh K.
supporting information, p. 1017 - 1021 (2020/01/25)
Transition-metal-free regioselective synthesis of functionalized amino-indenones by the reaction of ortho-alkynylaldehydes with a broad range of primary amines by intramolecular cyclization has been described. The designed reaction proceeds through KOH-mediated Prins-type cyclization and DMSO-promoted oxidation of the cyclopent-2-en-1-one system. The proposed mechanism and role of solvent were well supported by control experiments. For the first time, we have disclosed the reverse reactivity of (2-alkynyl)-arylaldimines in a super basic system.
Gold-Catalyzed Cyclization of 2-Alkynylaldehyde Cyclic Acetals via Hydride Shift for the Synthesis of Indenone Derivatives
Yamada, Tsuyoshi,Park, Kwihwan,Tachikawa, Takumu,Fujii, Akiko,Rudolph, Matthias,Hashmi, A. Stephen K.,Sajiki, Hironao
supporting information, p. 1883 - 1888 (2020/03/03)
An efficient gold-catalyzed cyclization of 2-alkynylaldehyde cyclic acetals has been developed for the synthesis of indenone derivatives. A wide variety of functionalized indenone derivatives can be obtained in good-to-excellent yields. HMBC and NOESY NMR analyses and mechanistic elucidation experiments revealed that the cyclization occurs via a 1,5-H shift. The cyclic acetal group promoted the 1,5-H shift by activating the benzylic C-H bond and preventing the migration of the alkoxy group by tethering both alkoxy groups.
C-H bond functionalization via hydride transfer: Formation of α-arylated piperidines and 1,2,3,4-tetrahydroisoquinolines via stereoselective intramolecular amination of benzylic C-H bonds
Vadola, Paul A.,Carrera, Ignacio,Sames, Dalibor
experimental part, p. 6689 - 6702 (2012/10/18)
We here report a study of the intramolecular amination of sp3 C-H bonds via the hydride transfer cyclization of N-tosylimines (HT-amination). In this transformation, 5-aryl aldehydes are subjected to N-toluenesulfonamide in the presence of BF3?OEt2 to effect imine formation and HT-cyclization, leading to 2-arylpiperidines and 3-aryl-1,2,3,4- tetrahydroisoquinolines in a one-pot procedure. We examined the reactivity of a range of aldehyde substrates as a function of their conformational flexibility. Substrates of higher conformational rigidity were more reactive, giving higher yields of the desired products. However, a single substituent on the alkyl chain linking the N-tosylimine and the benzylic sp3 C-H bonds was sufficient for HT-cyclization to occur. In addition, an examination of various arenes revealed that the electronic character of the hydridic C-H bonds dramatically affects the efficiency of the reaction. We also found that this transformation is highly stereoselective; 2-substituted aldehydes yield cis-2,5-disubstituted piperidines, while 3-substituted aldehydes afford trans-2,4-disubstituted piperidines. The stereoselectivity is a consequence of thermodynamic control. The pseudoallylic strain between the arene and tosyl group on the piperidine ring is proposed to rationalize the greater stability of the isomer with the aryl ring in the axial position. This preferential placement of the arene is proposed to affect the observed stereoselectivity.
