First total synthesis of four natural prenylated flavonoids

A facile approach for the first total synthesis of prenylated flavonoids, (±)-abyssinone-VI-4-O-methyl ether 1, (±)-abyssinone- IV-4'-O-methyl ether 2, (±)-abyssinone-V-4'-O-methyl ether 3 and (±)-sigmoidin E 4 has been described. The key intermediate 4-hydroxy-3, 5-di-(3-methylbut-2-enyl)benzaldehyde 6 was also first synthesized that features regioselective prenylation of 4-hydroxybenzaldehyde and crystallizing with petroleum ether from the reaction mixture by freeze-out effect.