Synthesis of planar chiral ferrocenyl cyclopentadienyl chelate ligand precursors

Two families of planar chiral ferrocenyl cyclopentadienyl chelate ligands for use in ansa-half sandwich metallocene complexes of catalytically active transition metals are described. The first family was derived in 4–5 steps from an enzymatic resolution of 1-iodo-2-(methylalcohol)ferrocene and possesses a cyclopentadiene derivative [Cp(H) = 1-indenyl, 2-indenyl or Ph4Cp(H)] directly attached to the ferrocene ring with an adjacent vicinal tether CH2Z donor group (Z = OH, OMe, NHMe, NMe2 or PPh2). The second family was derived from a chiral auxiliary approach and has the donor group (Z = PPh2 or NMe2) attached directly to the ferrocene ring with an adjacent tether vicinal CH2Cp(H) group [Cp(H) = Cp(H), fluorenyl, 1-indenyl, Me4Cp(H) or Ph4Cp(H)]

Part I: Synthesis of novel purely planar chiral ferrocenes for aysymetric synthesis: Part II: Synthesis of novel azaferrocenylboronic acids

Part I : Synthesis of Novel Purely Planar Chiral Ferrocenes for Asymmetric Synthesis The first part of the thesis describes the design and synthesis of a series of 1,2-bidendate purely planar chiral ferrocenyl ligand (Ligand A, B, C). The planar chirality was established using Kagan’s Directed ortho Metallation (DoM) strategy. Introduction of the desired α–cyclopentadienyl moiety proved to be difficult using nucleophilic substitution. This was circumvented by utilising Stone’s fulvene formation method, followed by reduction of the corresponding fulvene. The synthesised ligands were then subjected to complexation studies. In general, the obtained complexes proved to be unstable. Despite the instability issue, their activity was tested in several asymmetric catalytic processes (Diels-Alder reaction, reconstitutive condensation, allylic substitution), however no enantio-induction was detected. In the course of extending the scope of the Stone method, it was applied to different cyclopentadienyl type (indenyl, fluorenyl, tetramethylcyclopentadienyl) systems successfully. In addition, the synthesis of a novel ferrocene linked dimer is given. This ligand showed moderate activity in allylic alkylation reaction. Part II : Synthesis of Novel Azaferrocenylboronic Acids Based on Whiting’s preliminary report a novel azaferrocenylboronic acid structure was envisaged. The best synthetic approach consisted of two steps. The aryl functionality was introduced at the 2-position of the azaferrocene ring in a Negishi cross coupling reaction, which was followed by a lithium-halogen exchange/boronylation sequence. Boronylations under different conditions were tested, however, isolation of the target boronic acid was unsuccessful probably due to its instability. Introduction of the borane functionality was achieved by using a modified boronylating agent and the resulting azaferrocenylborane proved to be stable. A monohydroxyboronic acid was isolated, which might be a candidate for asymmetric direct amide bond forming reactions

A simple molecule-based octastate switch

Dithienylethene oxazolidine hybrid system connected through an isomerizable double bond exists under eight molecular states on demand. Combinations of electrocyclization of dithienylethene, Z/E isomerization and acid–base oxazolidine change cause selective addressabilities. Two intricate gated photochromic performances allow the execution of an 8-step molecular switch, which renders this molecular system the most complex known up to date

FPM model calculation for micro X-ray fluorescence confocal imaging using synchrotron radiation

A novel quantitative reconstruction model for synchrotron-based confocal X-ray fluorescence imaging has been developed and validated. The theoretical approach uses a new generalized system of equations of the Fundamental Parameter Method (FPM) to calculate the 2D distribution of the concentration values of the trace, minor, and major elements. For the reconstruction procedure of the 2D quantitative mXRF calculations, a serial-type specialised iterative algorithm was developed based on successive approximation of the elementary composition of each individual voxel in the sample. This procedure is capable of neglecting serious numerical difficulty arising at the simultaneous-approaching solution of the huge number of variables involved in the non-linear FPM equations. The model describes the absorption of the primary and secondary X-ray beams in the sample volume and the photoelectric excitation process of characteristic X-ray emission in each sample voxel. For validation of this new evaluation method, standard samples were measured using monoenergetic synchrotron radiation at beamline L in HASYLAB