Stereoselective Synthesis of the Optical Isomers of a New Muscarinic Receptor Antagonist, HL‐031120

Abstract

We present here a practical stereoselective synthetic method to produce enantiopure isomers of a new muscarinic receptor antagonist, HL‐031120 (3‐quinuclidinyl‐2′‐cyclopentyl‐2′‐hydroxy‐2′‐phenylacetate, I). Four optical isomers were effectively by stereoselective synthesized using pivaldehyde as steric hindrance agent from the chiral starting material, (S) or (R)‐mandelic acid. The isomers were obtained with 70–76% yields in 98–99% e.e.

Keywords:

• Muscarinic receptor antagonist
• stereoselective synthesis
• tertiary α‐hydroxy acid

Acknowledgment

We are gratefully acknowledge financial support from the National Natural Science Foundation of China (No. 203900508).