A PDE4 Inhibitor and its Enantiomers

Rolipram (1) is a selective inhibitor of phosphodiesterases 4 (PDE4s). PDE4s are responsible for hydrolysis of the cyclic nucleotides cAMP and cGMP to 5'-AMP and 5'-GMP, respectively, particularly in nerve and immune cells. The inhibition of PDE4s by 1 induces the elevation of intracellular cAMP concentration. Consequences 1-induced elevation of cAMP suppress expression of proinflammatory cytokines and other mediators of inflammation.¹⁾ 1 has been reported as a drug for the treatment of autoimmune diseases, Alzheimer’s disease, cognitive enhancement, and respiratory diseases like asthma and Chronic Obstructive Pulmonary Disease (COPD).
　

(R)-(−)-Rolipram (2) is the active enantiomer of 1, and has been reported that 2 is approximately 3 times more potent than (S)-(+)-rolipram (3) against PDE4s.²⁾ In 2015, Kobayashi et al. have been reported a new multistep continuous-flow synthesis of 2 and 3 using only columns packed with a chiral heterogeneous catalyst, respectively.³⁾ The reactions proceed smoothly without the isolation of any intermediates and without the separation of any catalysts, co-products, by-products, and excess reagents.

The product is for research purpose only.