Design and Synthesis of BACE-1 Inhibitors : Novel Compounds Targeting an Aspartic Protease Important in the Pathogenesis of Alzheimer’s Disease

Sammanfattning: This thesis deals with the design and synthesis of protease inhibitors targeting the aspartic protease BACE-1 (?-site APP cleaving enzyme-1), an enzyme important in the pathogenesis of Alzheimer’s disease. The inhibitors are evaluated with respect to inhibition data, in a structure-activity relationship part.Alzheimer’s disease is a disabling, progressive and ultimately fatal form of dementia afflicting approximately 40 percent of the population over 80 years, with over 30 million people suffering from Alzheimer’s disease worldwide. This makes Alzheimer’s disease the most common form of dementia. The identification of the amyloid-? peptide (A?) as the main constituent of extracellular plaques, which characterize Alzheimer’s disease, suggests that A? plays a vital role in the pathology of Alzheimer’s disease. The formation of A? occurs when amyloid-? precursor protein (APP) is cleaved by ?-secretase (BACE-1) and ?-secretase, which differ in length by 39-42 amino acids. This suggests that ?-secretase is a suitable target for the development of therapeutics against Alzheimer’s disease.The synthetic work of this thesis comprises development of BACE-1 inhibitors containing a hydroxyethylene (HE) central core transition state isostere. The target molecules were readily synthesized from chiral carbohydrate starting materials. Highly potent inhibitors were produced by varying the substituents coupled to the HE central core. Selecting an aryloxymethyl P1 side-chain and a methoxy P1’ side-chain resulted in exceptionally potent BACE-1 inhibitors that also exhibit high selectivity over cathepsin D. In a further development, the ether oxygen linkage in the P1 side-chain was removed, resulting in a carba analogue, providing improved potency in a cell-based assay.