The Organocatalytic Approach to Enantiopure 2H- and 3H- Pyrroles: Inhibitors of the Hedgehog Signaling Pathway

A divergent approach to enantioenriched 2H- and 3H-pyrroles catalyzed by a spirocyclic phosphoric acid is reported that makes use of a Fischer-type indolization and a [1,5]-alkyl shift. Catalyzed by the chiral phosphoric acid STRIP, good to excellent yields and enantioselectivities could be obtained. Remarkably, biological evaluation reveals one of these novel 2H-pyrroles to be a potent but nontoxic inhibitor of the Hedgehog signaling pathway by binding to the Smoothened protein

Asymmetric Catalysis on the Nanoscale: The Organocatalytic Approach to Helicenes

The first asymmetric organocatalytic synthesis of helicenes is reported. A novel SPINOL-derived phosphoric acid, bearing extended -substituents, catalyzes the asymmetric synthesis of helicenes through an enantioselective Fischer indole reaction. A variety of azahelicenes and diazahelicenes could be obtained with good to excellent yields and enantioselectivities

Organocatalysts for enantioselective synthesis of fine chemicals: definitions, trends and developments

Organocatalysis, that is the use of small organic molecules to catalyse organic transformations, has been included among the most successful concepts in asymmetric catalysis and it has been used for the enantioselective construction of C-C, C-N, C-O, C-S, C-P, and C-halide bonds. Since the seminal works in early 2000, the scientific community has been paying an ever-growing attention to the use of organocatalysts for the synthesis, with high yields and remarkable stereoselectivities, of optically active fine chemicals of interest for the pharmaceutical industry. A brief overview is here presented about the two main classes of substrate activation by the catalyst: covalent organocatalysis and non-covalent organocatalysis, with a more stringent focus on some recent outcomes in the field of the latter and of hydrogen-bond-based catalysis. Finally, some successful examples of heterogenisation of organocatalysts are also discussed, in the view of a potential industrial exploitation