A CONVENIENT SYNTHESIS OF NOVEL SPIROISOINDOLONE γ-HALOBUTYROLACTONES VIA HALOCYCLIZATION OF γ-ETHYLENIC ACIDS

摘要

γ-Ethylenic carboxylic acids are cyclized to spiroisoindolone γ-halomethylbutyrolactones, in the presence of NBS or NIS and K2CO3. The corresponding haloaspirobutyrolactones were isolated in high yields (57-95%). In the years since its discovery in the early 1900s, halolactonization has proven to be a versataile reaction in organic synthesis, allowing facile formation of small or medium ring size lactones from γ-unsaturated carboxylic acids, esters or amides.