Regioselective Reduction of 3-Substituted <i>N</i>-Acylpyrazinium Salts toward the Synthesis of 1,2-Dihydropyrazines
作者:Alfred L. Williams、Valentine R. St. Hilaire、Tina Lee
DOI:10.1021/jo202498r
日期:2012.4.20
The regioselectivereduction of 3-substituted N-acylpyrazinium salts with n-Bu3SnH has been developed for the synthesis of 3-substituted 1,2-dihydropyrazines in yields of 56–94%. Substitution of the pyrazinium salts with electron-donating groups favors the formation of the 1,2-isomers as a result of their better stability over the 1,6-isomers. Under mild acidic conditions, 3-methoxy substituted 1,2-dihydropyrazine
A palladium-catalyzed intramolecular Heck/Hydrogenation approach towards the synthesis of praziquantel
作者:Alfred L. Williams、Valentine R. St. Hilaire
DOI:10.1016/j.tet.2017.10.006
日期:2017.11
developed. Utilization of a palladium-catalyzedintramolecular Heck reaction to form dehydro-PZQ followed by a Hydrogenation step, in a stepwise or one-pot manner, allowed for the gram scale synthesis of PZQ in 4 or 5 steps and in good overall yields. This methodology proved to be well suited for generating the pyrazino[1,2-a] isoindole and pyrazino[1,2-a] benzazepine analogues of PZQ.