Silver-Catalyzed Synthesis of Spiroisoindole-butyrolactones

Significance

Reported is the formation of spirocenters on the isoindolone framework through the use of the known 5-exo-dig silver carbonate ­cyclization of alkynoic acids. The isoindolones are synthesized in high yield in four steps from homo­phthalic acid. The procedure gives high yields with short reaction times and the conditions are tolerant of a range of R groups, including alkynes. However, as may be expected, the R = H derivative undergoes rapid decarboxylation and gives only moderate yields (˜40% using a modified procedure). Investigations into the synthesis of chirally pure products were conducted and showed moderate success.