Efficient Synthesis of (Z)-4-((Substituted phenylamino)methyl­idene)isoquinoline-1,3(2H,4H)-diones Using the Eschenmoser Coupling Reaction

Abstract

AbstractA novel synthetic strategy involving the Eschenmoser coupling reaction of 4-bromoisoquinoline-1,3(2H,4H)-diones with substituted thioformanilides, thioacetanilides, and thiobenzanilides gave 18 (Z)-4-((substituted phenylamino)methylidene)isoquinoline-1,3(2H,4H)-diones. The reaction occurs under mild conditions (DMF or MeCN, 25–60 °C) without any base or thiophile and in good yields (43–95%). Furthermore, for the synthesis of starting thioformanilides carrying basic substituents, a new thioacylation protocol was developed that involves a thioacylating agent formed from carbon disulfide and lithium triethylborohydride.