479-59-4Relevant articles and documents
Acceptorless dehydrogenative condensation: synthesis of indoles and quinolines from diols and anilines
Bellezza, Delia,Zaragozá, Ramón J.,José Aurell,Ballesteros, Rafael,Ballesteros-Garrido, Rafael
supporting information, p. 677 - 683 (2021/02/06)
The use of diols and anilines as reagents for the preparation of indoles represents a challenge in organic synthesis. By means of acceptorless dehydrogenative condensation, heterocycles, such as indoles, can be obtained. Herein we present an experimental and theoretical study for this purpose employing heterogeneous catalysts Pt/Al2O3and ZnO in combination with an acid catalyst (p-TSA) and NMP as solvent. Under our optimized conditions, the diol excess has been reduced down to 2 equivalents. This represents a major advance, and allows the use of other diols. 2,3-Butanediol or 1,2-cyclohexanediol has been employed affording 2,3-dimethyl indoles and tetrahydrocarbazoles. In addition, 1,3-propanediol has been employed to prepare quinolines or natural and synthetic julolidines.
Iridium-Catalyzed Sustainable Access to Functionalized Julolidines through Hydrogen Autotransfer
Labed, Amira,Jiang, Fan,Labed, Ilhem,Lator, Alexis,Peters, Marius,Achard, Mathieu,Kabouche, Ahmed,Kabouche, Zahia,Sharma, Gangavaram V. M.,Bruneau, Christian
, p. 1090 - 1096 (2015/04/14)
The straightforward and ecofriendly preparation of functionalized julolidines starting from tetrahydroquinoline, diols, and aldehydes, for which water is produced as the only side product was investigated. To achieve this task, several well-defined ruthenium and iridium complexes including three new complexes were prepared from the corresponding phosphine-sulfonates, phosphine-carboxylates, and phosphine-phosphonates. The first transformation involved in situ generation of enaminoiminium intermediates, which allowed the formation of the julolidines through formal N,C(sp2)-cyclization of tetrahydroquinoline and the propane-1,3-diols. The influence of the chelate acidity points out that [Cp?IrIII]-based catalysts (Cp?=C5Me5) featuring phosphine-carboxylate and phosphine-sulfonate ligands were suitable for the cyclization, whereas the acidic phosphinophosphonate-containing complex favored the formation of reduced N-alkylated tetrahydroquinoline. We found that substitution of the propane-1,3-diols was crucial for the generation of enaminoiminium ions, which accounts for the efficiency and selectivity of the reaction. Applying another hydrogen autotransfer process, the prepared julolidines were easily functionalized at the C2 position.
A traceless perfluoroalkylsulfonyl (PFS) linker for the deoxygenation of phenols
Pan, Yijun,Holmes, Christopher P.
, p. 2769 - 2770 (2007/10/03)
(Equation presented) The synthesis of a novel perfluoroalkylsulfonyl (PFS) fluoride is described for use as a traceless linker in solid-phase organic synthesis. Attachment to the resin and subsequent coupling of a phenol affords a stable arylsulfonate that behaves as a support-bound aryl triflate. Palladium-mediated reductive cleavage of a wide variety of phenols generated the parent arenes. The resin-bound aryl triflate was shown to be stable to reductive amination conditions, and the traceless synthesis of Meclizine is reported.
