Syntheses of β-resorcylic acid derivatives, novel potato micro-tuber inducing substances isolated from Lasiodiplodia theobromae

The syntheses of β-resorcylic acid derivatives 1 and 2, isolated from fungus Lasiodiplodia theobromae, and their dimethyl ethers were accomplished. (R)-(−)-1,3-Butanediol was used as a chiral source of the side chain C6-synthon. The dianion of the benzoic acid moiety was alkylated with C6-bromide to give the desired skeleton. Several β-resorcylic acid derivatives including 1 and 2 were synthesized via hydrogenation, lactonization, demethylation and esterification. The (R)-configuration of the stereogenic center in the side chain was proved by this synthesis. It is confirmed that two phenolic hydroxy groups are required for 1 and 2 to exhibit potato micro-tuber inducing activity.