A straightforward synthesis of 2(3),6,6-trimethyl- 6,7-dihydrobenzofuran-4(5H)-ones

Alkylation of dimedone with 1,2,3-trichloro- or 1,2,3-tribromopropanes in the presence of K₂CO₃ in DMSO follows both O- and C-alkylation pathways giving 3-(2-haloprop-2-enyloxy)-5,5-dimethylcyclohex-2-enone and 2-(2-haloprop-2-enyl)-3-hydroxy-5,5-di- methylcyclohex-2-enone. These compounds on heating afford 3,6,6-trimethyl- and 2,6,6-trimethyl-6,7-dihydrobenzofuran-4(5H)-ones, respectively.