The Total Synthesis of (+/-)-Pisiferin

Article abstract of DOI:10.1246/bcsj.59.3103

The conversion of racemic α-cyclocitral into 3-(3-isopopyl-4-methoxyphenethyl)-4,4-dimethyl-2-methylenecyclohexanone (2) was carried out in five steps via 3-(3-isopropyl-4-methoxyphenethyl)-2,4,4-trimethyl-1-cyclohexene.An intramolecular cyclization of 2 with polyphosphoric acid produced the corresponding two tricyclic ketones possessing cis- and trans-A/B ring junctions.Each of these ketones was further converted into 12-mesyloxy-9(10->20)-abeo-abieta-1(10),8,11,13-tetraene in four steps.The mesylate was reduced with lithium aluminium hydride to give (+/-)-pisiferin.