Anthranilimide-based glycogen phosphorylase inhibitors for the treatment of Type 2 diabetes: 2. Optimization of serine and threonine ether amino acid residues

Optimization of the amino acid residue of a series of anthranilimide based glycogen phosphorylase inhibitors is described leading to the identification of serine and threonine ether analogs. t-Butylthreonine analog 20 displayed potent in vitro inhibition of GPa, low potential for P450 inhibition, and excellent pharmacokinetic properties.