acetone + hexanal ---[aq. NaOH]---> 3-nonen-2-one 47% [1]
3-nonen-2-one + dimethylmalonate ---[NaOMe]---> complicated intermediate 70% [2]
complicated intermediate ---DMF, Br2, heat---> olivetol 85% [3]
[1] J. Gen. Chem. USSR 33, 134 (1963)
[2, 3] J. Org. Chem. 42, 3456 (1977)
best olivetol synth I know so far. Cheap, easy, yields ok. Starting with another aldehyde will yield olivetol analogs.