Studies on the Catalytic Asymmetric Fischer Indolization

This work describes further developments and applications of the catalytic asymmetric Fischer indolization. In the first part of this thesis, the development of an organocatalytic asymmetric synthesis of helicenes via a Fischer indolization is discussed. The application of a novel SPINOL-derived phosphoric acid, featuring extended π-surfaces as 3,3‘-substituents which can potentially participate in π-interactions with the polyaromatic intermediate, afforded the corresponding products in high yields and enantioselectivities. The second part of this work describes the development of a catalytic asymmetric dearomatizing synthesis of 1,4-diketones via an interrupted Fischer indolization. Employing aryl hydrazines with α-substituents next to the hydrazine group prevents the rearomatization which takes place in common Fischer indole syntheses, thus enabling the hydrolysis of the generated diimine species. In the presence of STRIP as catalyst, a variety of different 1,4-diketones could be obtained in generally high yields, diastereo- and enantioselectivities. The last part of this thesis deals with the development of an organocatalytic asymmetric stereodivergent synthesis of novel 3H- and 2H-pyrroles, applying an interrupted Fischer indolization and for the 2H-pyrroles a subsequent stereospecific [1,5]-alkyl shift. Employing STRIP as catalyst afforded the corresponding products in good to excellent yields and enantioselectivities. Preliminary biological investigations of these novel structure motifs in cell-based assays, monitoring biological signal transduction pathways showed an inhibition of the Hedgehog signaling pathway in a μM range

Crystal structure of [5-n-butyl-10-(2,5-dimethoxyphenyl)-2,3,7,8,13,12,17,18-octaethylporphyrinato]nickel(II)

The asymmetric unit of the title nickel(II) porphyrin, [Ni(C48H60N4O2)], contains one independent molecule. The average Ni—N bond length is 1.917 (13) Å. The molecules are arranged in a closely spaced lattice structure in which neighbouring porphyrins are oriented in inversion-related dimers. The nickel(II) porphyrin is characterized by a significant degree of a ruffled (B1u) conformation with small contributions from saddle (B2u) and wave (y) [Eg(y)], as determined using normal structural decomposition. Disorder in the 2,5-dimethoxyphenyl substituent was modelled over two positions with a 60% occupancy for the major moiety. One of the ethyl groups is also disordered over two positions and was modelled with the major moiety being present in 51.3% occupancy

Crystal structure of 5-tert-butyl-10,15,20-triphenylporphyrin

In the title free base porphyrin, C42H34N4, the neighbouring N...N distances in the center of the ring vary from 2.818 (8) to 2.998 (8) Å and the phenyl rings are tilted from the 24-atom mean plane at angles varying between 62.42 (2)–71.63 (2)°. The NH groups are involved in intramolecular bifurcated N—H...(N,N) hydrogen bonds. The Ca—Cm—Ca angles vary slightly for the phenyl rings, between 124.19 (18)–126.17 (18)°. The largest deviation from the mean plane of the 24-atom macrocycle is associated with the meso carbon at the substituted tert-butyl position, which is displaced from the mean plane by 0.44 (2) Å. The free base porphyrin is characterized by a significant degree of ruffled (B1u) distortion with contributions from domed (A2u) and wave [Eg(y) and Eg(x)] modes. In the crystal, molecules are linked by a number of weak C—H...π interactions, forming a three-dimensional framework. The structure was refined as a two-component inversion twin

Large-Scale Assessment of Binding Free Energy Calculations in Active Drug Discovery Projects

Here we present an evaluation of the binding affinity prediction accuracy of the free energy calculation method FEP+ on internal active drug discovery projects and on a large new public benchmark set.<br /