Discovery of 7-tetrahydropyran-2-yl chromans: β-site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitors that reduce amyloid β-protein (Aβ) in the central nervous system

J Med Chem. 2014 Feb 13;57(3):878-902. doi: 10.1021/jm401635n. Epub 2014 Jan 22.


In an attempt to increase selectivity vs Cathepsin D (CatD) in our BACE1 program, a series of 1,3,4,4a,10,10a-hexahydropyrano[4,3-b]chromene analogues was developed. Three different Asp-binding moieties were examined: spirocyclic acyl guanidines, aminooxazolines, and aminothiazolines in order to modulate potency, selectivity, efflux, and permeability. Using structure-based design, substitutions to improve binding to both the S3 and S2' sites of BACE1 were explored. An acyl guanidine moiety provided the most potent analogues. These compounds demonstrated 10-420 fold selectivity for BACE1 vs CatD, and were highly potent in a cell assay measuring Aβ1-40 production (5-99 nM). They also suffered from high efflux. Despite this undesirable property, two of the acyl guanidines achieved free brain concentrations (Cfree,brain) in a guinea pig PD model sufficient to cover their cell IC50s. Moreover, a significant reduction of Aβ1-40 in guinea pig, rat, and cyno CSF (58%, 53%, and 63%, respectively) was observed for compound 62.

MeSH terms

  • Amyloid Precursor Protein Secretases / antagonists & inhibitors*
  • Amyloid beta-Peptides / metabolism*
  • Animals
  • Aspartic Acid Endopeptidases / antagonists & inhibitors*
  • Brain / metabolism*
  • CHO Cells
  • Cell Line, Tumor
  • Chromans / chemical synthesis*
  • Chromans / pharmacokinetics
  • Chromans / pharmacology
  • Cricetinae
  • Cricetulus
  • Crystallography, X-Ray
  • Guinea Pigs
  • HEK293 Cells
  • Humans
  • Macaca fascicularis
  • Male
  • Mice
  • Models, Molecular
  • Pyrans / chemical synthesis*
  • Pyrans / pharmacokinetics
  • Pyrans / pharmacology
  • Rats
  • Rats, Sprague-Dawley
  • Spiro Compounds / chemical synthesis*
  • Spiro Compounds / pharmacokinetics
  • Spiro Compounds / pharmacology
  • Stereoisomerism
  • Structure-Activity Relationship


  • Amyloid beta-Peptides
  • Chromans
  • Pyrans
  • Spiro Compounds
  • Amyloid Precursor Protein Secretases
  • Aspartic Acid Endopeptidases
  • BACE1 protein, human

Associated data

  • PDB/4N00