Thionoesters as 1,2‐Dipolarophiles for [4+2] Cycloaddition with Cyclobutanones

Ni-Catalyzed Synthesis of Thiocarboxylic Acid Derivatives

A Ni-catalyzed cross-coupling of readily accessible O-alkyl xanthate esters or thiocarbonyl imidazolides and organozinc reagents for the synthesis of thiocarboxylic acid derivatives has been developed. This method benefits from a fast reaction time, mild reaction conditions, and ease of starting material synthesis. The use of transition-metal catalysis to access a diverse range of thiocarbonyl-containing compounds provides a useful complementary approach when compared with previously established methodologies.

Synthesis of 5-(1-Alkoxyalkylidene)tetronates by Direct Condensation Reactions of Tetronates with Thionolactones and Thionoesters

We report a two-step approach to bicyclic and monocyclic 5-(1-alkoxyalkylidene)tetronates starting from lactones/esters. The method features the use of thionolactones and thionoesters as activated forms of lactones/esters that allows the direct condensation with tetronates via one-pot enolate formation, nucleophilic addition, S-methylation, and DBU-promoted elimination. The value of the method was demonstrated by the stereoselective syntheses of two natural products: 5,6-Z-fadyenolide (Z/E ratio = 6:1) and 9,10-methylenedioxy-5,6-Z-fadyenolide (Z/E ratio = 9:1).