Traceless solid-phase synthesis of heteroannulated 1,3-oxazin-6-ones.

A microwave-assisted solid-phase synthesis of heteroannulated 1,3-oxazin-6-ones has been developed. Significant rate enhancement was observed for all steps carried out under microwave irradiation, and the overall reaction time was dramatically shortened when compared to the conventional procedures. A representative set of 20 bi- and tricyclic heteroannulated 1,3-oxazin-6-ones was prepared.

Traceless solid-phase synthesis and biological evaluation of purine analogs as inhibitors of multidrug resistance protein 4.

The traceless solid-phase syntheses of 6-oxopurines and pyrazolo[3,4-d]pyrimidines are presented. The effects of these compounds on multidrug resistance protein 4 (MRP4/ABCC4) facilitated efflux was examined. Four of the compounds, 7b, 7c, 15a, and 17e, were active in inhibiting MRP4-mediated efflux of the bimane-glutathione conjugate.