Summary The anions of thiophenol, methyl malonate and malononitrile react with 3-methyl- 5, 6-dihydro-2 (4 H)-benzofuranone (lc) by the formation of the corresponding 1, 6-addition products cis-5c (63%), trans-6 (42%) and trans-7 (76%), respectively. Likewise, the reaction of 3-methyl-5-methylidene-2 (SH)-furanone (1 b) with thiophenol yields the 1, 6-addition product 5b (66%), and with the sodium salt of methyl acetoacetate the 1, 6-addition ...