Reagent-free synthesis of 2,3,4-polysubstituted tetrahydroquinolines: application to the formal synthesis of (±)-martinellic acid and martinelline

Synthesis of the Hexahydropyrrolo-[3,2-c]-quinoline Core Structure and Strategies for Further Elaboration to Martinelline, Martinellic Acid, Incargranine B, and Seneciobipyrrolidine

Natural products are rich sources of interesting scaffolds possessing a plethora of biological activity. With the isolation of the martinella alkaloids in 1995, namely martinelline and martinellic acid, the pyrrolo[3,2-c]quinoline scaffold was discovered. Since then, this scaffold has been found in two additional natural products, viz. incargranine B and seneciobipyrrolidine. These natural products have attracted attention from synthetic chemists both due to the interesting scaffold they contain, but also due to the biological activity they possess. This review highlights the synthetic efforts made for the preparation of these alkaloids and formation of analogues with interesting biological activity.

Organocatalytic Asymmetric Three-Component Povarov Reactions of Anilines and Aldehydes

We report the first highly enantio- and diastereoselective three-component Povarov reaction between anilines and aldehydes catalyzed by a chiral amine catalyst. A wide variety of substituted tetrahydroquinolines were obtained with moderate to good yields and excellent enantioselectivity and diastereoselectivity (up to 99% ee and >95:5 dr) under the reaction conditions. Furthermore, the reaction intermediates could be efficiently converted to other valuable building blocks.

Progress in the Chemistry of Tetrahydroquinolines

Tetrahydroquinoline is one of the most important simple nitrogen heterocycles, being widespread in nature and present in a broad variety of pharmacologically active compounds. This Review summarizes the progress achieved in the chemistry of tetrahydroquinolines, with emphasis on their synthesis, during the period from mid-2010 to early 2018.

Highly regio- and diastereo-selective synthesis of novel tri- and tetra-cyclic perhydroquinoline architectures via an intramolecular [3 + 2] cycloaddition reaction

A facile and efficient synthetic protocol was established for the construction of novel tri- and tetra-cyclic pyrrolo/pyrrolizinoquinoline architectures via the in situ formation of azomethine ylide followed by an intramolecular [3 + 2] cycloaddition reaction strategy. This protocol leads to the creation of two/three new rings and three/four contiguous stereocentres, in which one of them is a tetra-substituted carbon center, in a highly diastereoselective fashion with excellent yields.

Enantioselective Total Synthesis of (-)-Martinellic Acid

An enantioselective total synthesis of martinellic acid is described. The pyrroloquinoline alkaloid core is efficiently prepared from a quinoline, employing a method which relies on a newly developed Cu-catalyzed enantioselective alkynylation using the chiral imidazole-based biaryl P,N ligand StackPhos to establish the absolute stereochemistry. The remaining carbon atoms are then installed by means of a diastereoselective Pd-catalyzed decarboxylative allylation and the synthesis is completed after straightforward functional-group manipulation. This new synthetic method enables the most concise enantioselective synthesis of this important class of molecules to date.