An Improved Synthesis of Dichloro-pyrazinones

Significance

Reported is an improved synthesis of highly functionalized dichloropyrazinones. The original synthesis first put forward by Hoornaert (J. Heterocycl. Chem. 1983, 20, 919) achieved the final cyclization either by conventional heating at 80-100 ˚C for 4-6 h or stirring at room temperature for two days. The present improved procedure uses microwave heating to significantly ­reduce the reaction time (2 x 10 min). This has ­allowed the rapid construction of a library of compounds. To further illustrate the power of this method, the new Hepatitis C virus NS3 protease inhibitor A was synthesized.

Book: Microwave-Assisted Synthesis of Heterocycles, In Topics in Heterocyclic Chemistry, Vol. 1; E. Van der Eycken, C. O. Kappe, Eds.; Springer Verlag: Berlin, Heidelberg, 2006.