This thesis describes two different projects. The first project deals with the design, synthesis and biological activity of novel reversible peptidyl FVIIa inhibitors (Chapter 1–3). FVIIa was launced as NovoSeven R over a decade ago by Novo Nordisk for the treatment of hemophilia A and B complicated by antibodies. FVIIa is a serine protease and hence liquid formulations are not stable due to autoproteolysis. A reversible inhibitor would stabilize FVIIa making a liquid formulation possible, representing an important follow-up product for Novo Nordisk. Peptidyl benzyl ketones was chosen as a new class of potential inhibitors, whose sequence was rationally selected from a previously reported FVIIa-TF specificity profile. Since arginine was found to be the most active P1-amino acid, a mild and efficient synthesis of the corresponding arginyl benzyl ketone building block was sought. Two stategies were proposed, the one involving a tetramic acid key intermediate being the most straightforward and with less protective group manipulation. For introduction of the benzyl functionality, a palladium-catalyzed -arylation was developed. This transformation occurs under mild conditions showing high functional group tolerance. Unfortunately, these -aryl tetramic acids were too unreactive and ring opening toward the synthesis of the building block did not succeed. However, -aryl tetramic acids are still interesting compounds due to their potential biological activity. The building block 3.15 (P1) was instead synthesized via a Weinreb amide and a small library of peptides were prepaired by solution-phase Boc/Bn-synthesis. Different P3-P2 sequences (tyrosine, threonine, phenylalanine, leucine) and N-terminals (P4 = H-, Ac-, BnSO2- and Cbz-) were investigated. Unfortunately, O-debenzylation was found to be very difficult which restricted the number of peptides containing tyrosine and threonine. Cbz-D-Phe-Phe-Arg-bk (3.50) was identified as the most potent FVIIa inhibitor with a Ki = 8 μM (IC50 = 16 μM) and with a 35- and 28-fold selectivity against thrombin and FXa, respectively, but with a poor solubility in aqueous media. A SAR study revealed that especially a bulky aromatic Cbz-terminal was crucial for potency. In the view of potency and selectivity, 3.50 seems to be a promising candidate for future development of liquid formulations of NovoSeven R . The second project deals with the rhodium-catalyzed enantioselective synthesis of diaryl amines, which is an important class of compounds (Chapter 4). For example it is found in the third generation anti-histaminic agent levocetirizine. Development of efficient synthetic routes is therefore of considerably interest. The rhodium-catalyzed enantioselective synthesis employing -carbamoyl sulfones and arylboronic acids was therefore investigated using the chiral ligand (R,R)-deguPHOS. Rh(acac)(coe)2 was originally utilized requiring the use of a glovebox, but through catalyst screening [RhCl(cod)]2 was found to be equally efficient. Contrary to Rh(acac)(coe)2, this new catalyst is air-stable, commercially available and inexpensive. [RhCl(cod)]2 and (R,R)-deguPHOS was preincubated prior to use to secure excellent enantioselectivity. A cannulation technique was implemented for application outside the glovebox. A low content of boroxine in the batch of arylboronic acid was found to be crucial for a satisfactory outcome. The highly functionalized diaryl amine 4.13 was synthesized in good yield and excellent enantioselectivity in gram-scale. The absolute configuration was determined by X-ray crystallography to be the (S)-enantiomer. The improvements make the reaction very usable and efficient for synthesis of important amine drug candidates.